iENCES 
LIBRARY 


AMERICAN  PERMIAN  VERTEBRATES 


THE  UNIVERSITY  OF  CHICAGO  PRESS 
CHICAGO,  ILLINOIS 


THE  BAKER  &  TAYLOR  COMPANY 

NEW  YORK 

THE  CAMBRIDGE  UNIVERSITY  PRESS 

LONDON   AND   EDINBURGH 


AMERICAN  PERMIAN 
VERTEBRATES 


BY 


SAMUEL  W.  WILLISTON 

Professor  of  Paleontology  in  the 
University  of  Chicago 


THE  UNIVERSITY  OF  CHICAGO  PRESS 
CHICAGO,  ILLINOIS 


.>   •        ^ 

EARTH 
SCIENCES 
LIBRARY 


COPYRIGHT  1911  BY 
THE  UNIVERSITY  OF  CHICAGO 

All  Rights  Reserved 


Published  October  1911 


Composed  and  Printed  By 

The  University  of  Chicago  Press 

Chicago,  Illinois,  U.S.A. 


CONTENTS 

INTRODUCTION i 

Cacops  Bone-Bed 4 

Craddock  Bone-Bed 5 

Permian  of  New  Mexico 7 

CLASS  AMPHIBIA;  SUBCLASS  STEGOCEPHALA 9 

Order  Temnospondyli 9 

Family  Eryopidae 9 

Eryops  grandis 10 

Aspidosaurus  novomexicanus 12 

Aspidosaurus  peltatus 13 

CLASS  REPTILIA 15 

Order  Cotylosauria 15 

Family  Diadectidae 16 

Nothodon  lentus 16 

Diadectes,  species 23 

Family  Limnoscelidae 23 

Limnoscelis  paludis 23 

Family  Seymouriidae 48 

Seymouria  baylorensis 48 

Family  Pariotichidae 68 

Captorhinus,  species 68 

Captorhinus  illinoiensis 69 

Order  Theromorpha . . . , 70 

Family  Sphenacodontidae 72 

Clepsydrops 72 

Clepsydrops  natalis 73 

Xaosaurus,  species 75 

Sphenacodon  ferox 78 

Family  Poliosauridae-f 80 

Ophiacodon  minis 81 

Yaranosaurus  brevirostris 85 

Family  Caseidae in 

Casea  broilii 112 

Trispondylus  texensis   131 

Genus  incertae  sedis 135 

Platyhystrix  rugosus 135 

Species  incertae  sedis 137 

EXPLANATION  OF  PLATES 140 

INDEX 145 

PLATES  I-XXXYIII 


24177:5 


INTRODUCTION 

The  present  work  comprises  a  series  of  monographic  studies, 
together  with  briefer  notes  and  descriptions,  of  new  or  little-known 
amphibians  and  reptiles  from  the  Permian  deposits  of  Texas  and 
New  Mexico. 

The  material  upon  which  these  studies  are  based  was,  for  the 
most  part,  collected  during  recent  years  by  field  parties  from  the 
University  of  Chicago  under  the  charge  of  Mr.  Paul  Miller,  assistant 
curator  of  paleontology  in  the  University  of  Chicago,  or  of  myself. 
The  earlier  collections  of  the  University  from  Texas,  made  by  Pro- 
fessor Case,  have  been  discussed  by  him  in  various  papers,  especially 
in  his  monograph  on  the  Pelycosauria,  published  by  the  Carnegie 
Institution  in  1908.  In  addition,  I  am  permitted,  by  the  kindness 
of  Professor  Schuchert,  to  include  herein  the  results  of  the  investi- 
gations by  myself  of  the  Permian  collections  from  New  Mexico 
in  the  Yale  Museum.  In  order  that  these  results  may  have  a 
greater  homogeneity  than  they  would  otherwise  I  repeat  the  descrip- 
tion of  the  genus  Limnoscelis  published  in  the  American  Journal  of 
Science  for  May,  1911,  with  additions,  omissions,  and  corrections. 
For  the  privilege  of  examining  these  important  collections,  so  long 
neglected,  and  of  publishing  the  results  of  my  studies,  I  would  here 
express  my  sincere  thanks  to  Professor  Schuchert.  Farther  on  I 
give  some  data  regarding  the  type  collections  of  Professor  Marsh 
from  these  New  Mexico  regions,  and  brief  notes  concerning  the  New 
Mexico  fauna,  as  represented  in  these  collections,  will  be  found  in 
the  cited  paper.  I  do  not  repeat  them  here,  since  a  proposed  further 
exploration  of  these  deposits  by  Professor  Case  in  conjunction  with 
myself  will  doubtless  furnish  much  more  extensive  and  accurate 
information  concerning  them  and  their  fauna,  which  will  be  pub- 
lished later  by  us.  I  may  also  say  here  that>,  in  the  future,  it  is 
proposed  by  Professor  Case  and  myself  to  publish  the  results  of  our 
investigations  of  this  important  fauna,  so  long  neglected,  under 
joint  authorship. 

It  is  not  my  intention,  however,  to  neglect  the  further  exploration 


2  AMERICAN  PERMIAN  VERTEBRATES 

of  the  Texas  deposits,  opportunity  permitting.  The  Texas  Permian 
fauna  is  yet  but  imperfectly  known;  of  the  not  less  than  thirty-five 
genera  of  land  vertebrates  recorded  from  those  beds  or  known  to  me, 
scarcely  a  third  are  satisfactorily  known;  and  the  region  is  by  no 
means  exhausted.  Careful  search  is  sure  to  yield  many  new  forms 
and  more  perfect  specimens  of  others  hitherto  imperfectly  known. 
I  may,  however,  here  express  a  caution  that  none  save  the  most 
experienced  collectors  need  attempt  their  further  exploration  with 
much  hope  of  success.  The  beds  are  the  most  difficult  of  exploita- 
tion of  any  known  to  me  in  a  field  experience  of  thirty-five  years. 
Usually  the  fossils  are  more  or  less  hidden  in  concretionary  nodular 
masses,  almost  invisible  or  indistinguishable  to  the  untrained  eye 
until  they  have  been  broken  up  and  weathered,  when  the  inclosed 
fossils  have  lost  much  of  their  value.  Rarely  single  bones  and  even 
whole  skeletons  are  found  in  clay  deposits  almost  or  quite  free  from 
matrix,  but  many  such  are  not  to  be  expected. 

In  the  following  pages  I  have  not  thought  it  worth  while  to 
enter  extensively  into  many  suggested  morphological  and  taxonomi- 
cal  discussions.  In  my  experience  in  vertebrate  paleontology 
speculations  based  upon  imperfect  and  incomplete  material,  while 
often  fascinating  as  giving  free  rein  to  the  imagination,  are  usually 
in  the  end  found  to  be  worthless  and  even  misleading.  The  chief 
need  in  the  paleontology  of  the  early  vertebrates  is  more  facts, 
many  more  facts,  and  I  have  little  faith  in  any  system  of  classifi- 
cation based  upon  our  present  knowledge  of  these  older  land  verte- 
brates. I  shall  hope  to  know  enough  about  the  vertebrates  of  the 
American  Permian  in  the  course  of  a  few  years  to  venture  to  present 
my  views  of  their  phylogenies,  but  at  present  these  views  are  largely 
hypothetical.  As  Dr.  Broom,  in  a  letter  to  me,  has  said,  of  a 
few  groups  of  reptiles,  like  the  dinosaurs,  crocodiles,  pterosaurs, 
phytosaurs,  rhynchosaurs,  etc.,  we  are  justified  in  holding  definite 
opinions,  but  as  regards  most  of  the  other  groups,  often  called  orders, 
we  are  less  sure  than  we  were  a  dozen  years  ago.  The  more  recent 
general  classifications  of  the  reptiles  by  Cope,  Osborn,  Boulenger, 
and  others  have  offered  suggestions  of  value,  but  they  are  by  no 
means  the  real  solutions  of  the  reptilian  and  amphibian  phylogenies. 
The  recent  classifications  of  Jaekel  are  not  to  be  taken  seriously. 


INTRODUCTION  3 

Certain  morphological  problems  I  have  discussed  in  the  following 
pages,  and  I  have  given  what  seems  to  me  to  be  the  legitimate 
conclusions  regarding  the  immediate  relationships  of  the  forms  under 
discussion.  The  present  work,  however,  is  offered  more  as  a  con- 
tribution to  our  knowledge  of  ancient  reptiles  and  amphibians, 
with  such  summaries  and  definitions,  based  chiefly  on  American 
forms,  as  our  present  knowledge  permits.  The  illustrations  of  the 
work  throughout  are  by  myself. 

All  the  forms  from  the  Texas  deposits  mentioned  or  described 
in  the  following  pages  as  of  specimens  which  I  have  studied,  come 
from  the  upper  or  Clear  Fork  division. 

Mr.  Cummins  has  recently  given  an  annotated  list1  of  the  various 
genera  of  the  Texas  Permian  with  their  localities  or  horizons, 
so  far  as  could  be  obtained.  My  own  experience  quite  confirms 
his  opinion  that  there  is  a  distinction  between  the  faunas  of  the 
Wichita  and  Clear  Fork  divisions  (no  vertebrates  are  known,  so 
far  as  I  am  aware,  from  the  Double  Mountain  division  above  the 
Clear  Fork,  though  footprints  do  occur  in  the  shales  of  that  division). 
The  collections  made  by  the  University  of  Chicago  expeditions  in 
Texas  the  past  few  years  have  been  almost  exclusively  from  the 
Clear  Fork  division.  These  collections  embrace,  to  the  best  of  my 
recollection,  the  following  forms: 

Amphibia:  Lysorophus,  Diplocaulus ,  Trimerorhachis  (appar- 
ently absent  from  the  upper  part),  Eryops,  Cacops,  Dissorophus, 
Aspidosaurus,  Cardiacephalus. 

Reptilia:  from  the  uppermost  beds,  Labidosaurus,  Naosaurus, 
Dimetrodon;  from  lower  horizons,  Naosaurus,  Dimetrodon,  Clepsy- 
drops,  Varanosaurus,  Trispondylus,  Casea,Araeoscelis,  Captorhinus, 
Diadectes,  Seymouria,  etc. 

Perhaps  the  most  characteristic  of  the  upper  beds  is  Labido- 
saurus, of  the  lower,  Cricotus,  and  their  horizons  may  be  known  as 
the  Labidosaurus  and  Cricotus  zones.  On  the  other  hand  I  feel 
quite  confident  that  no  definite  line  can  be  made  between  the  two 
divisions,  and  at  present  Clear  Fork  can  be  used  in  a  general  way 
to  designate  the  upper,  and  Wichita  the  lower,  part  of  the  Texas 
deposits. 

1  Journal  of  Geology,  XVII  (1908),  737. 


4  AMERICAN  PERMIAN  VERTEBRATES 

Many  of  the  most  important  and  interesting  specimens  obtained 
by  us  on  these  expeditions  come  from  two  isolated  deposits  which 
I  call  the  Cacops  and  Craddock  bone-beds,  concerning  which  and 
the  forms  found  in  them  the  following  will  be  of  use. 

Cacops  Bone-Bed 

Seldom  in  the  history  of  paleontological  exploitation  has  there 
been  found  a  more  remarkable  deposit  of  early  land  vertebrates 
than  that  to  which  I  give  the  name  of  the  Cacops  bone-bed,  because 
of  the  genus  the  remains  of  which  occur  most  abundantly  in  it. 
The  immediate  locality  of  this  deposit  is  about  five  miles  west  of  the 
Vernon  road  in  the  valley  of  the  Wichita,  not  far  from  Indian  Creek. 
The  deposit  was  discovered  by  Mr.  Miller  in  the  autumn  of  1909, 
from  a  large  quantity  of  washed-out  bones  lying  in  a  small  gully 
near  the  foot  of  some  rather  precipitous  exposures.  Only  a  por- 
tion of  the  remains  were  exhumed  at  the  time  of  the  discovery; 
the  bed  was  thoroughly  worked  out  by  Mr.  Miller  the  following 
year. 

The  numerous  skeletons  contained  in  the  deposit  lay  upon  each 
other  through  a  thickness  of  about  two  feet  or  a  little  more;  those 
near  the  top  were  more  isolated,  those  lower  down  packed  more 
closely  together  and  more  disturbed  in  their  relations.  As  a  rule 
the  various  skeletons  are  more  or  less  united,  but  frequently  legs, 
tails,  and  even  single  bones  are  found  isolated.  The  material  in 
which  the  remains  occur  is  the  dark  red  clay  forming  the  greater 
part  of  the  exposures  of  the  Texas  Permian  deposits,  but  the  bones 
themselves  are  incrusted  with  a  thin,  more  or  less  adherent,  hard 
matrix,  sometimes  removable  with  difficulty.  The  bones  of  the  upper 
layers  have  a  less  thick  incrustation,  but  in  the  lower  ones  the 
skeletons  lie  more  closely  packed  together,  the  skeletons  or  parts 
of  skeletons  often  being  cemented  together  in  masses  of  considerable 
size.  Because  of  this  it  is  often  difficult  to  separate  any  one  skele- 
ton without  disturbing  the  others.  The  remains  lay  in  a  space  some 
six  or  seven  feet  in  width  by  ten  or  twelve  in  length.  As  a  rule  the 
skeletons  lie  prone,  but  some  have  been  found  in  a  supine  position. 
To  develop  all  the  skeletons  or  parts  of  skeletons  in  the  deposit 
would  require  the  uninterrupted  time  of  a  skilful  preparator  for 


INTRODUCTION  5 

not  less  than  two  or  three  years.  As  such  an  expenditure  of  time  is 
neither  practicable  nor  desirable  at  present,  all  that  has  been  done 
so  far,  in  addition  to  those  needed  for  study  and  exhibition,  is  the 
separation  of  the  various  skeletons,  so  far  as  possible,  from  the  clay 
in  which  they  were  imbedded,  leaving  them  connected  and  associ- 
ated by  the  cementing  matrix.  The  material  was  brought  to  the 
laboratory  in  bandaged  blocks  of  various  sizes  from  fifty  to  four 
hundred  pounds  in  weight,  as  it  was  found  most  convenient  in 
the  field  to  divide  them.  And  even  the  preliminary  separation  of 
the  skeletons  has  been  done  for  but  little  more  than  half  of  the 
material  secured — done  in  the  hope  of  finding  other  forms  than 
those  discovered  in  the  earlier  examination.  And  this  hope  has 
been  in  part  fulfilled.  As  this  work  goes  to  press  a  skeleton  or  part 
of  a  skeleton  of  another  form,  a  very  large  species  of  Captorhinus, 
has  been  discovered.  Among  the  skeletons  and  parts  of  skeletons 
so  far  worked  out,  in  part  or  wholly,  there  are  at  least  a  dozen 
skeletons  of  Varanosaurus,  as  many  or  more  of  Cacops,  including 
eight  or  ten  good  skulls,  five  or  six  of  Casea,  the  skeleton  of  Capto- 
rhinus just  mentioned,  and  a  few  bones  of  Seymouria.  Not  the 
slightest  indication  of  any  large  or  very  small  animal  has  been 
found  so  far.  Of  the  species  found  among  these  skeletons,  none 
was  known  to  the  earlier  explorers  of  the  Texas  Permian,  unless 
it  be  Seymouria,  as  represented  in  the  fragmentary  skull  to  which 
the  name  Conodectes  was  given  by  Cope.  One  was  described  by 
Broili  seven  years  ago,  and  three  at  least  and  probably  four  are 
new. 

The  Cacops  bone-bed  lies,  as  well  as  I  can  estimate,  two  hundred 
feet  at  least  below  the  topmost  exposure  of  the  Clear  Fork  division, 
about  in  the  same  horizon  as,  though  perhaps  a  little  higher  than, 
and  about  six  miles  distant  from,  the  Craddock  bone-bed. 

Craddock  Bone-Bed 

This  deposit  of  bones,  to  which  frequent  reference  is  made  in 
the  following  pages,  was  discovered  in  the  autumn  of  1909  by  Mr. 
Lawrence  Baker  of  the  University  of  Chicago  expedition,  near  the 
west  line  of  the  Craddock  ranch,  and  about  six  miles  northwest 
of  Seymour,  Texas.  The  bones  in  this  deposit  extend  through  a 


6  AMERICAN  PERMIAN  VERTEBRATES 

thickness  of  about  one  foot  over  a  considerable  space,  a  few 
hundred  square  feet,  imbedded  in  red  clay  like  that  of  the  Cacops 
bed.  They  are,  unlike  those  of  the  Cacops  bed,  however,  for  the 
most  part  isolated,  and  generally  more  or  less  free  from  incrust- 
ing  matrix,  and  usually  in  the  most  perfect  preservation.  Not 
a  few,  however,  show  effects  of  erosion,  as  though  they  had  been 
rolled  upon  a  beach  of  hard,  shallow  bottom.  It  is  impossible 
at  present  to  determine  with  assurance  the  taxonomic  position  of 
many  of  the  isolated  bones;  nor  can  they  be  determined  until  the 
fauna  of  the  Texas  Permian  is  much  better  known  than  is  the  case 
at  the  present  time.  That  there  are  representatives  of  several 
new  genera  and  species  among  the  remains  secured  is  practically 
certain,  but  I  hesitate  to  give  names  to  isolated  parts  of  the  skeleton 
unless  such  parts  are  very  characteristic,  rendering  the  species 
recognizable  in  the  future  with  certainty.  The  material  secured 
includes  two  or  three  hundred  bones,  none  of  them  associated 
save  those  of  Araeoscelis.  Among  these  I  have,  so  far,  determined 
the  following:  Di  metro  do  n,  represented  by  D.  incisivus,  and  D. 
gigas,  and  perhaps  another  species;  an  allied  theromorph  reptile 
with  a  longer  skull  than  that  of  Dimetrodon,  but  with  a  dentition 
very  different,  an  undoubted  new  genus;  numerous  vertebrae  of  a 
very  large  species  of  Diadectes;  numerous  limb  bones,  girdles,  etc., 
which  I  refer  to  Clepsydrops  natalis,  together  with  others  of  an 
allied  more  slender-limbed  species ;  a  number  of  vertebrae  and  limb 
bones  of  Seymouria;  a  single  femur  of  a  pariotichid  shown  in 
Plate  XXXII,  Figs.  6,  7;  at  least  two  genera  of  small  reptiles 
represented  by  numerous  limb  bones,  etc.;  and  perhaps  half  a 
dozen  skeletons  more  or  less  incomplete,  all  found  together  in  a 
space  of  a  few  square  feet,  of  the  slender  little  reptile  which  I  have 
called  Araeoscelis.  Among  the  amphibian  material,  Trimerorha- 
chis  is  represented  by  intercentra  and  parts  of  the  skull;  Diplocaulus 
by  characteristic  skull  and  vertebral  bones;  and  at  least  three 
species  of  either  Aspidosaurus  or  allied  genera.  In  addition  there 
are  a  few  spines  of  two  types  of  sharks. 

The  Araeoscelis  material  has  not  yet  been  fully  prepared,  but 
I  doubt  not  that  it  is  sufficient  to  make  out  most  of  the  skull  and 
skeleton  characters.  The  skull  has  a  single  temporal  vacuity  of 


INTRODUCTION  7 

large  size,  the  body  and  tail  are  very  long  and  slender,  the  pelvis 
of  the  pelycosaurian  or  V aranosaurus  type,  and  the  feet  appear 
to  be  very  much  like  those  of  the  last-named  genus,  save  that  the 
limbs  are  very  much  more  slender.  The  genus  seems  to  be  very 
closely  allied  to,  possibly  identical  with,  Kadaliosaurus  from  the 
European  Permian. 

I  have  given  numerous  figures  of  some  of  the  most  characteristic 
smaller  bones  in  this  bone-bed,  not  only  because  of  their  unusual 
perfection  but  because  of  their  faunistic  association. 

Permian  of  New  Mexico 

Since  the  brief  paper  by  Marsh  in  the  American  Journal  of 
Science  for  May,  1878,  is  rather  inaccessible  and  isolated  I  have 
quoted  his  descriptions  in  the  discussions  of  his  types,  and  here 
give  the  introductory  part  of  the  paper  as  follows: 

The  United  States  Survey  of  the  Fortieth  Parallel,  in  charge  of  Mr.  Clarence 
King,  has  made  known  the  fact  that  a  well-marked  Permian  horizon  can 
be  distinguished  in  the  Rocky  Mountain  region;  and  deposits  considered  of 
this  age  are  represented  on  the  geological  maps  of  that  survey.  This  adds  much 
interest  to  the  vertebrate  fauna  known  from  near  this  horizon,  and  probably 
belonging  to  it,  as  hitherto  no  Permian  vertebrates  have  been  identified  in  this 
country,  although  not  uncommon  in  Europe. 

The  Museum  of  Yale  College  contains  an  extensive  series  of  reptilian 
remains  belonging  to  a  peculiar  lacustrine  fauna,  which  includes  also  amphibi- 
ans and  fishes.  These  fossils  are  from  several  localities  in  the  West,  but 
mainly  from  New  Mexico,  and  the  geological  horizon  appears  to  be  in  the  upper 
portion  of  the  Permian.  These  reptilian  remains  are  in  excellent  preservation, 
and  among  them  are  several  genera  having  the  more  important  characters  of  the 
Rhynchocephalia,  of  which  the  genus  Hatter ia,  of  New  Zealand,  is  the  living 
type.  The  principal  points  of  agreement  are  the  separate  premaxillaries,  the 
immovable  quadrate,  and  the  biconcave  vertebrae.  Another  character  of 
much  interest  is  the  presence  of  certain  hypaxial  elements  of  the  vertebrae, 
first  observed  by  von  Meyer  in  the  Triassic  genus  Sphenosaurus,  and  called 
by  him  intercentral  bones  (Zwichenwirbelbein  [sic]).  These  wedge-shaped 
bones  are  apparently  the  homologues  of  the  cervical  hypopophyses  in  the 
Mosasauria,  and  of  the  subcaudal  attachments  in  the  Odontornithes,  and  a 
few  recent  birds.  These  intercentral  ossifications  apparently  exist  in  all  the 
reptilia  yet  found  in  this  new  fauna,  and  hence  serve  to  distinguish  it.  With 
this  character  is  another  of  hardly  less  interest.  The  anterior  rib-bearing 
vertebrae  preserved  have  three  separate  articular  facets  for  the  ribs;  one  on 
the  anterior  part  of  the  centrum  for  the  head,  and  a  double  one  above  for  the 


8  AMERICAN  PERMIAN  VERTEBRATES 

bifid  tubercle.    In  the  implantation  of  the  teeth  and  their  successional  develop- 
ment, these  reptiles  resemble  the  Mosasaurs. 

These  characters,  with  others  mentioned  below,  indicate  two  distinct 
families,  which  may  be  called  the  Nothodontidae  and  Sphenacodontidae,  from 
the  typical  genera  here  described. 

Tliis  paper  by  Marsh,  of  which  the  foregoing  is  the  introductory 
part,  was  actually  published  on  May  3,  1878,  five  days  prior  to 
the  publication  by  Cope  of  his  paper  on  the  Texas  fauna  contain- 
ing the  description  of  numerous  new  forms,  and  in  which  was  pro- 
posed the  family  Clepsydropidae  and  the  suborder  Pelycosauria,  a 
preliminary  notice  of  which  was  published  in  the  American 
Naturalist  for  May,  1878,  distributed  (fide  Cope)  on  April  22,  giving 
priority  to  several  of  the  generic  names  which  later  appeared  in 
his  Paleontological  Bulletin,  No.  29.  The  further  history  of  the 
publication  of  these  papers  makes  one  of  the  most  regrettable 
pages  in  the  scientific  and  personal  controversy  between  these 
two  eminent  men  and  need  not  be  given  here.  Those  who  are 
curious  may  find  further  details  concerning  it  in  a  paper  published 
by  Cope  the  following  month  in  the  American  Naturalist  (June, 
1878).  Suffice  it  here  to  say  that  the  names  proposed  by  Marsh  in 
his  paper  have  an  actual  priority  of  five  days  in  publication  over 
those  of  Professor  Cope,  as  distributed  in  his  Paleontological  Bul- 
letin, No.  29,  and  over  all  the  names  applied  to  the  Texas  Permian 
vertebrates  save  that  of  Eryops,  purporting  to  have  been  published 
the  preceding  November,  and  those  published  without  description 
by  Cope  in  the  American  Naturalist,  for  May,  1878,  as  follows: 

Diadectes,  Bolosaurus,  Epicordylus,  Empedocles,  Parioxys,  Tri- 
merorhachis,  and  Rhachitomiis . 

Under  the  strict  rules  of  priority,  as  formulated  by  the  Inter- 
national Committee  on  Nomenclature,  even  these  names  cannot 
claim  priority  over  those  ot  Marsh,  since  they  were  merely  nomina 
nuda.  If,  however,  any  student  would  deny  priority  to  them 
after  reading  the  paper  by  Cope  in  the  June  number  of  the  Natural- 
ist, he  may;  but  I  shall  not. 

All  of  Marsh's  types  came  from  a  bone-bed.  Very  few  of  the 
bones  were  in  anatomical  relation,  and  numerous  individuals  of 
six  or  seven  forms  are  represented  among  them.  I  designate  the 
bed  as  the  Baldwin  bone-bed,  in  the  descriptions. 


Class  AMPHIBIA 
Subclass  STEGOCEPHALA 

Cope,  Extinct  Batrachia,  Aves,  and  Reptilia  of  North  America,  p.  6,  1868 
(Stegocephali,  order). 

Order  TEMNOSPONDYLI 

Zittel,  Handbuch  der  Paleontologie,  III,  380,  1888. 

Small  to  laige,  terrestrial  stegocephalians,  especially  charac- 
terized by  the  large  size  of  the  intercentra,  and  the  paired  pleuro- 
centra.  Skull  with  all  membrane  bones  of  air-breathing  verte- 
brates; more  or  less  rugose;  a  parietal  foramen  present;  teeth 
more  or  less  labyrinthine,  attached  to  premaxillae,  maxillae, 
dentaries,  vomers,  palatines,  and  pterygoids;  at  least  two  large 
conical  teeth  on  the  palate.  Parasphenoid  usually  large,  rarely 
vestigial;  pterygoid  vacuities  large.  From  twenty-one  to  twenty- 
four  ( ?)  presacral  vertebrae;  tail  short  or  moderately  long,  rhachito- 
mous  or  embolomerous,  that  is,  composed  of  two  disks,  one  bear- 
ing the  chevrons  and  arch,  the  other  intercalated;  chevrons 
always  forming  a  part  of  the  large  intercentrum.  Clavicular 
girdle  sometimes  large,  with  rugose  markings;  at  other  times 
smaller  and  smooth,  the  interclavicle  never  with  a  long  posterior 
stem;  a  clei thrum  always  present.  Scapula  and  coracoid  fused; 
a  supracoracoid  foramen  present,  as  also  a  supraglenoid.  Humerus 
rarely  with  entepicondylar  foramen.  Carpus  ossified;  hand 
pentedactylate.  Pelvis  fully  ossified,  without  puboischiadic  vacu- 
ity; a  pubic  or  obturator  foramen  piercing  the  pubes.  Tarsus 
ossified,  the  intermedium  pedis  always  distinct;  at  least  three 
ossa  centralia;  feet  pentedactylate.  Ventral  and  dorsal  ossifica- 
tions often  present. 

Family  Eryopidae 
Cope,  American  Naturalist,  XVI,  334,  1882. 

Spines  of  vertebrae  simple,  or  expanded  distally,  sometimes 
into  a  close-fitting  or  imbricated,  more  or  less  dilated,  carapace; 


io  AMERICAN  PERMIAN  VERTEBRATES 

otic  notch  never  closed  behind;  no  dorsal  dermal  ossifications; 
a  single  pair  of  sacral  ribs;  tail  long;  ribs  with  uncinate  processes ; 
parasphenoid  large. 


Eryops  grandis  Marsh. 

Ophiacodon  graiidis  Marsh,  American  Journal  of  Science,  XV,  211,  May  3, 
1878.     Rio  Arriba  County,  New  Mexico. 

?  Eryops  reticulatus  Cope,  American  Naturalist,  1881;    ibid.,  34,  1884; 
Trans.  Amer.  Phil.  Soc.,  XVI.     New  Mexico. 

A  second,  larger  species  of  apparently  the  same  genus  [Ophiacodon]  is  repre- 
sented by  portions  of  the  jaws,  and  teeth,  and  various  parts  of  the  skeleton. 
In  this  species  the  dentary  bone  is  angular  at  its  anterior  extremity,  and 
triangular  in  section.  Its  external  surface  is  rugose,  as  in  the  crocodiles.  The 
crowns  of  the  teeth  are  striate  at  the  base,  and  the  latter  is  furrowed  vertically. 
The  teeth  are  not  so  thickly  set  as  in  the  smaller  species,  and  the  bases  of  the 
crowns  are  somewhat  transverse. 

MEASUREMENTS 

Space  occupied  by  ten  anterior  lower  teeth 140  mm. 

Depth  of  lower  jaw  at  symphysis 129 

Antero-posterior  extent  of  symphysis 25 

Depth  of  dentary  bone  below  seventh  tooth 30 

Width  of  dentary  at  this  point 20 

The  present  species  was  about  ten  feet  in  length,  and  the  largest  reptile 
yet  found  in  this  fauna.  The  remains  are  from  New  Mexico. 

Among  the  material  studied  by  Marsh  from  the  Baldwin  bone- 
bed  there  is  a  considerable  portion  of  a  skeleton,  probably  all  of 
one  individual,  of  this  species.  The  left  mandible,  with  all  its 
teeth  broken  away,  the  type  specimen,  has  been  made  much  more 
complete  than  when  Marsh  described  it.  In  addition,  there  are 
parts  of  another  mandible,  numerous  intercentra,  pleurocentra, 
and  neurocentra,  the  larger  part  of  two  scapulae,  etc.  Among  the 
later  collections  from  the  same  bone-bed  there  are  two  more  or 
less  complete  skulls,  two  scapulae,  a  pelvis,  portions  of  limb  bones, 
and  numerous  vertebrae.  All  these  parts  probably  belong  to  the 


AMPHIBIA  :  ERYOPS  n 

one  species,  though  this  cannot  be  positively  decided  without 
further  study  and  more  material.  The  species  is  rather  small  for 
an  Eryops,  though  it  must  unfortunately  bear  the  name  grandis, 
a  name  given  to  it  under  the  misapprehension  that  it  was  a  reptile. 
Evidently  Marsh  had  not  seen  the  description  of  Eryops  megacepha- 
lus  Cope  at  the  time  of  the  publication  of  his  paper;  otherwise 
he  would  not  have  fallen  into  the  error  of  calling  his  species 
a  reptile.  The  description  of  E.  megacephalus  is  said  to  have 
been  published « the  preceding  November,  but  of  this  there  is 
some  doubt.  That  there  were  " various  parts  of  the  skeleton" 
among  the  material  studied  by  Marsh  must,  of  course,  have  been 
assumed,  since  he  could  not  have  recognized  them  without  at  the 
same  time  recognizing  their  generic  distinction  from  Ophiacodon 
minis. 

A  considerable  number  of  species  of  Eryops  have  been  described 
from  Texas  and  New  Mexico,  but  we  are  almost  entirely  ignorant 
yet  of  the  real  distinguishing  specific  characters,  and  their  differen- 
tiation has  been,  for  the  most  part,  assumed. 

In  a  recent  paper  I  stated  that  Eryops  had  no  uncinate  processes 
on  the  ribs;  in  this  I  was  in  error.  The  specimen  of  Eryops 
mounted  in  the  American  Museum — an  excellent  one — has  not 
only  well-developed  uncinate  processes,  but  ventral  ossifications 
as  well,  characters  which  associate  the  genus  much  more  closely 
with  the  European  Euchirosaurus  than  I  had  supposed.  In  the 
same  publication  I  also  spoke  of  a  specimen  with  dilated  spines 
which  I  was  inclined  to  refer  to  the  basal  caudal  region  of  Eryops. 
The  American  Museum  specimen  likewise  shows  that  there  were 
no  dilated  spines  anywhere  in  the  vertebral  series  in  Eryops,  from 
which  it  would  seem  certain  that  there  is  another  genus  of  Ery- 
opidae  in  Texas,  possibly  Anisodexis,  .even  more  closely  allied  to 
Euchirosaurus.  Because  of  this  close  relation  between  Eryops 
and  Euchirosaurus  with  dilated  spines,  and  also  because  of  the 
possession  of  the  uncinate  processes  on  the  ribs,  I  am  disposed 
to  place  the  genus  Aspidosaurus  in  the  same  family,  all  of  them, 
as  also  various  species  referred  in  the  past  provisionally  to  Zatrachys, 
presenting  these  characters  and  the  open  otic  notch  behind. 


12  AMERICAN  PERMIAN  VERTEBRATES 

ASPIDOSAURUS 
Broili,  Paleontographica,  LI,  1904. 

Aspidosaurus  novomexicanus,  n.  sp.  Plate  XXXVIII,  Fig.  i.  Rio 
Arriba  County,  New  Mexico.  Specimen  No.  810,  Yale 
Museum. 

The  type  specimen  of  this  species  is  inclosed  in  a  hard,  rather 
fine-grained,  dark-red,  weather-worn  sandstone  nodule,  which  is 
worked  with  some  difficulty.  The  front  extremities,  most  of  the 
pectoral  girdle,  save  the  left  scapula  and  the  upper  end  of  the  right 
one,  the  hind  girdles  and  hind  extremities,  and  the  tail  had  been 
eroded  away  before  the  specimen  was  discovered  by  Mr.  Baldwin. 
The  specimen  was  sent  in  with  specimen  No.  809  of  Limnoscelis 
paludis  Will.,  and  probably  had  been  picked  up  in  the  wash  among 
the  fragments  of  that  specimen. 

As  much  as  is  prudent  has  been  removed  of  the  matrix  covering 
the  bones,  as  shown  in  the  photograph.  The  skull  was  attached  to 
the  vertebral  column  at  an  angle  dorsalward  of  nearly  ninety 
degrees;  it  has  been  separated  and  placed  in  the  plane  of  the 
remainder  of  the  specimen;  it  has  lost  the  nasal  portion  and  much 
of  the  mandibles.  The  upper  surface  of  the  skull  is  markedly 
concave;  its  tabular  angles  are  moderately  produced  into  a  rounded 
extremity,  but  are  not  turned  downward  to  meet  the  quadrate, 
as  in  Cacops  and  Dissorophus.  The  temporal  region  has  a  deep 
emargination  not  unlike  that  of  Cacops,  though  not  inclosed 
behind  by  the  tabulare.  As  this  whole  region  was  covered  by  the 
sandstone  matrix,  the  absence  of  the  posterior  bar  cannot  be 
attributed  to  erosion,  nor  is  there  any  indication  that  such  a 
prolongation  of  the  tabularia  was  present  in  the  living  animal  and 
lost  in  fossilization,  especially  so  as  the  region  is  alike  on  the  two 
sides.  Of  course,  this  emargination  was  for  the  ear,  confirming 
my  views  as  to  the  nature  of  the  temporal  opening  in  Trematops, 
Cacops,  and  Dissorophus.  There  are  only  seven  dorsal  spinous 
shields,  the  first  of  which,  as  in  Dissorophus,  is  more  than  twice 
the  length  of  the  following  ones;  it  is  rounded  in  front.  The  last 
shield,  also,  is  much  broader  antero-posteriorly  than  from  side  to 
side.  The  shields  show  little  evidence  of  imbrication.  About 


AMPHIBIA:  ASPIDOSAURUS  13 

twenty  pairs  of  ribs  are  visible,  either  at  their  ends  or  from  above; 
and  doubtless  this  was  nearly  the  full  number  of  presacral  vertebrae. 
A  fragment  of  the  left  ilium  is  present,  and  on  the  right  side  there 
appear  to  be  two  sacral  ribs,  though  this  is  doubtful.  The  tail 
was  wholly  lost  before  fossilization.  The  ribs,  as  will  be  seen  from 
the  photograph,  have  the  uncinate  process  characteristic  of  Eryops, 
Euchirosaurus,  and  Aspidosaurus,  differentiating  the  form  at  once 
from  the  Trematopsidae  and  Dissorophidae.  These  processes  are 
more  slender  in  front,  where  they  approach  the  proximal  end  of  the 
rib.  Posteriorly  they  become  progressively  broader  and  more 
remote  from  the  proximal  end  till,  at  about  the  tenth  presacral 
vertebra,  they  are  merely  distal  expansions  of  the  ribs  themselves. 

Among  the  material  at  the  American  Museum  there  are  several 
small  skulls,  not  twice  the  size  of  the  present  species,  which  have 
been  referred  to  juvenile  specimens  of  Eryops.  In  one  of  these  I 
observe  that  the  otic  notch  is  relatively  large,  with  tabular  processes 
much  like  those  of  the  present  species.  I  suspect  that  this  skull, 
at  least,  is  really  that  of  a  species  of  Aspidosaurus. 

From  an  examination  of  the  tail  vertebrae  in  the  mounted 
specimen  of  Eryops  of  the  American  Museum,  I  find  the  same 
structure  as  that  figured  by  me  in  a  late  paper  as  coming  doubt- 
fully from  the  tail  of  either  Eryops  or  Trimerorhachis .  The  figured 
vertebrae  are  too  small  to  belong  with  an  adult  Eryops,  but  the 
structure  is  identical. 

An  examination  of  the  type  specimen  of  Otocoelus  mimeticus 
convinces  me  of  the  absolute  identity  of  the  genus  with  Dissorophus, 
as  previously  recognized  by  Case. 

^Aspidosaurus  peltatus,  n.  sp.     Plate  XXXII,  Fig.  7.     Craddock 
bone-bed,  Baylor  County,  Texas. 

Among  the  material  secured  from  the  bone-bed  on  Craddock's 
ranch,  as  described  on  a  previous  page,  there  are  at  least  two,  and 
possibly  three,  species  of  temnospondylous  amphibians  which  may, 
provisionally,  be  referred  to  this  genus.  Most  characteristic  of 
these  remains  is  the  dorsal  spinous  expansion  herewith  figured. 
This  dorsal  plate  has.  as  a  part  of  it,  the  upper  end  of  a  thin  dorsal 


14  AMERICAN  PERMIAN  VERTEBRATES 

vertebral  spine.  The  plate  is  gently  and  evenly  convex  above, 
slightly  convex  on  the  anterior  thinned  border,  and  correspondingly 
concave  on  the  posterior  thicker  border.  The  upper  surface  is 
rather  deeply  marked  by  irregular  pits  and  grooves,  as  is  seen  in 
the  photograph.  It  is  very  evident  that  the  plate  did  not  overlap 
the  preceding  plate,  as  is  the  case  in  A.  chiton  Broili,  the  genotype. 
In  the  middle  behind,  however,  the  flat  surface  of  the  spine  served 
to  help  support  the  following  dermal  plate. 

Associated  with  this  plate  in  the  bone-bed  are  a  considerable  num- 
ber of  femora,  and  several  humeri  of  the  types  figured  and  described 
by  me  in  the  Bulletin  of  the  Geological  Society  of  America,  XXI, 
270,  Plate  XV,  Figs.  4,  5.  The  most  typical  specimens  of  the 
femora  found  associated  with  the  type  are  shown  natural  size  in 
Plate  XXXIII,  Figs.  1-4,  and  Plate  XXXII,  Figs.  4,  6.  While  all 
these  femora  have  the  same  general  shape  and  high  adductor  crest, 
and  the  same  absence  of  condylar  ossification,  they  differ  very 
materially  in  their  slenderness,  especially  noticeable  in  Plate 
XXXII,  Fig.  4,  and  Plate  XXXIII,  Fig.  3.  That  one  or  the  other 
of  these  femora  and  one  or  the  other  of  the  types  of  humeri  figured 
in  the  cited  paper  belong  with  the  species  represented  by  the 
dermal  plate  is  quite  sure,  but,  as  it  is  impossible  to  determine 
which  of  them  should  bear  the  name  A .  peltatus,  the  dorsal  spinous 
expansion  shown  in  the  figure  may  be  considered  the  type  of  the 
species.  The  species  seems  nearest  related  to  A.  glascocki  Case, 
but  differs  materially  in  the  character  of  the  sculpture,  the  thickness 
of  the  plate,  and  the  relations  of  the  vertebral  spine  itself. 

There  are  various  small  intercentra  in  the  collection,  and  frag- 
ments of  jaws,  which  doubtless  belong  with  one  or  the  other  of  the 
species  represented  by  the  humeri  and  femora. 


Class  REPTILIA 

Order  COTYLOSAURIA 

Cope,  American  Naturalist,  334,  1880. 

Primitive,  crawling,  or  subambulatory,  terrestrial  reptiles,  of 
small  to  rather  large  size,  with  large  head,  short  or  no  neck,  heavy, 
thickset  body,  and  a  moderately  long  or  short  tail,  the  skin  either 
bare  or  with  bony  ossicles;  slender  ventral  ribs  rarely  present. 
Skull  stegocrotaphic,  with  all  or  nearly  all  dermal  bones  character- 
istic of  the  Stegocephala;  lachrymal  (postnarial,  adlachrymal) 
extending  to  the  nares;  septomaxillary  usually  if  not  always 
present;  postorbital  always  distinct;  dermoccipital  always,  and 
tabulare  and  supra  temporal  usually,  present;  a  parietal  foramen, 
sometimes  very  large;  paroccipital  (opisthotic)  separate;  stapes  large; 
pterygoids  articulating  with  vomers;  transpalatine  not  yet  demon- 
strated ;  teeth  thecodont  or  acrodont,  inserted  on  premaxillae,  max- 
illae, vomers,  palatines,  pterygoids,  dentaries,  and  sometimes  the 
splenials.  Prearticular  of  mandibles  separate;  splenial  entering 
into  mandibular  symphysis;  coronoid  of  moderate  size.  Verte- 
brae notochordal,  twenty- three  to  twenty-five  (?)  presacrals,  and 
one  or  two  sacrals;  intercentra  always  present.  Ribs  usually 
double-headed,  in  front,  at  least,  and  expanded  but  not  emarginate 
posteriorly,  sometimes  single-headed  or  double-headed  throughout, 
attached  to  intercentral  space  and  diapophysis;  free  ribs  on  base 
of  tail.  Vestigial  clei thrum  sometimes  present;  clavicles  large; 
interclavicle  expanded  anteriorly,  with  a  long  stem;  no  ossified 
sternum.  Coracoid  co-ossified  with  scapula;  sutural  division  be- 
tween coracoid  and  metacoracoid  in  glenoid  fossa;  a  supraglenoid 
canal  always  present.  Pubis  and  ischium  large,  plate-like,  with- 
out puboischiadic  vacuity,  but  with  an  obturator  foramen  piercing 
the  pubes;  ilium  more  or  less  dilated  posteriorly  above.  Humerus 
with  broadly  dilated  extremities,  in  very  divergent  planes;  an 
entepicondylar  foramen  always  present;  no  ectepicondylar  fora- 


1 6  AMERICAN  PERMIAN  VERTEBRATES 

men;  olecranon  moderately  produced.  Four  bones  in  the  proxi- 
mal row  of  the  carpus;  two  free  centralia,  and  five  carpalia; 
hand  pentedactylate ;  two  bones  in  proximal  row  of  tarsus,  a 
single  centrale  and  five  tarsalia;  feet  pentedactylate;  phalangeal 
formula,  usually,  if  not  always,  2,  3,  4,  5,  4  (3).  Anterior  ribs 
dilated  and  overlapping  in  all  known  American  forms. 

Family  Diadectidae 

Cope,  Proc.  Amer.  Phil.  Soc.,  XIX,  45,  1880;  Marsh,  American  Journal  of 
Science,  XC,  410,  1878  (Nothodontidae). 

Skull  short  and  high,  very  rugose  above;  parietal  foramen  very 
large;  prefrontals  and  postfrontals  meeting  broadly  over  orbits; 
a  broad  and  rather  deep  otic  emargination  in  posterior  temporal 
region.  The  single  row  of  teeth  in  maxillae  and  dentaries  deeply 
thecodont,  with  narrow,  transverse  crown  (except  the  most  anterior 
ones)  showing  a  median  cusp  and  a  lateral  lower  one  on  each 
side.  A  vestigial  clei thrum  present;  vertebrae  with  thick,  stout 
spines;  one  or  two  sacral  vertebrae  present;  usually  a  hyposphene 
and  hypantrum.  Tail  moderately  long  or  short.  Legs  short  and 
stout;  carpus  and  tarsus  fully  ossified,  the  proximal  carpal  and 
tarsal  bones  relatively  small;  ungual  phalanges  broad  and  flat;  no 
ventral  ribs. 

NOTHODON 

Marsh,  American  Journal  of  Science,  XV,  410,  May  3,  1878;  ?  Diadecles  Cope, 
American  Naturalist,  XII,  327,  1878  (published  April  22,  fide  Cope); 
Proc.  Amer.  Phil.  Soc.,  XVII,  205,  1878;  Paleontological  Bulletin,  No. 
29,  1878  (published  May  8,  fide  Cope). 

Nothodon  lentus  Marsh,  op.  cit.  Plate  XXXIV,  Figs.  5-7 ;  Plate 
XXXV,  Figs.  1-4;  Plate  XXXVI,  Fig.  2.  Rio  Arriba 
County,  New  Mexico.  Yale  Museum. 

This  genus  of  reptiles  may  readily  be  distinguished  by  the  dentition.  In 
each  separate  premaxilla  there  are  two  slender  pointed  teeth.  In  front  of  the 
maxillary  there  are  one  or  two  smaller  teeth,  followed  by  a  number  with 
transverse  crowns,  resembling  in  form  the  premolars  of  some  carnivorous 
mammals.  These  crowns,  when  unworn,  have  a  central  cusp,  and  on  each 
side  a  tubercle,  somewhat  like  that  on  the  premolars  of  the  genus  Canis.  In 


REPTILIA:  NOTHODON  17 

the  present  species  the  first  and  last  of  the  transverse  teeth  are  smaller  than  the 
middle  ones.  The  legs  were  short,  the  long  bones  had  their  extremities  covered 
with  cartilage,  but  the  carpals  and  the  tarsals  were  well  ossified.  The  centra 
were  very  deeply  concave,  and  the  tail  was  long. 

The  following  measurements  are  taken  from  the  type  specimen  of  this 
species: 

Length  of  maxillary  bone 65  mm. 

Space  occupied  by  ten  maxillary  teeth 55 

Height  of  crown  of  second  maxillary  tooth 14 

Height  of  crown  of  third  maxillary  tooth 9 

Antero-rJosterior  diameter 3 

Transverse  diameter 8 

Antero-posterior  diameter  of  eighth  tooth 5 

Transverse  diameter 15 

The  present  species  was  about  five  or  six  feet  in  length,  and  herbivorous  in 
habit.  It  was  apparently  slow  in  movement,  and  probably  more  or  less 
aquatic.  The  remains  at  present  known  are  from  New  Mexico. 

Among  the  material  from  the  Baldwin  bone-bed  of  New  Mexico 
in  the  Yale  Museum  which  had  been  received  at  the  time  the 
above  description  was  written,  I  find  evidence  of  three  individuals 
pertaining  to  this  species,  including  the  type  specimen  as  figured; 
fragmentary  remains  of  mandibles;  the  nearly  complete  upper  part 
of  two  skulls,  and  an  additional  frontal  bone;  radius,  ulna,  tibia, 
and  fibula.  The  skull  bones  were  widely  separated  and  scattered, 
and  none  of  the  bones  had  been  mended.  Whether  or  not  the 
animal  had  a  long  tail  it  is  even  yet  impossible  to  say  from  the 
specimens,  as  no  two  bones  are  in  relation  with  each  other. 

Among  the  material  acquired  later  there  are  evidences  of  addi- 
tional skulls,  but  with  the  scattered  and  incomplete  remains  of 
them  little  can  be  done.  Had  the  material  been  collected  with 
modern  care,  there  is  little  doubt  that  from  among  it  almost  perfect 
skulls  might  have  been  reconstructed,  of  especial  value  from  the 
fact  that  the  bones  are  free  from  matrix,  undistorted,  and  separated 
at  their  sutures,  with  few  exceptions.  Two  have  been  partially 
restored,  showing  nearly  the  whole  of  the  upper  surface. 

The  superior  surface  of  the  skull  is  roughened  throughout 
(Plate  XXXVIII),  save  the  supraoccipital  region,  with  small 
punctulations  and  deep,  pitlike  or  groovelike  excavations,  espe- 
cially conspicuous  over  the  parietal  and  frontal  bones.  From  near 


i8 


AMERICAN  PERMIAN  VERTEBRATES 


each  posterior  angle  (see  Fig.  i)  there  begins  a  distinct  groove, 
including  the  pit  mentioned  by  Case  in  Diadectes,  running  forward 
and  inward  on  each  side  of  the  pineal  vacuity,  and  on  the  frontal 
and  nasal  bones.  Opposite  the  postorbital  angle  there  is  a  branch 
leading  outward,  and  the  two  main  branches  seem  to  meet  in  a 

pit  in  the  middle  of  the  frontal 
bone,  with  a  branch,  or  a  dis- 
tinct groove  leading  forward  on 
the  anterior  part  of  the  nasals. 
That  these  are  mucous  grooves  is 
of  course  possible,  but  I  suspect 
that  they  are,  rather,  grooves  for 
the  passage  of  veins  beneath  a 
heavy  corneous  plate  which 
covered  the  whole  of  the  upper 
surface  of  the  skull. 

The  relations  of  the  skull 
bones,  so  far  as  they  have  been 
reconstructed,  of  course,  are  very 
positively  shown,  since  all,  save 
the  dermoccipital,  were  wholly 
separated  at  their  sutures. 
These  relations  I  show  in  the 
accompanying  outline  figure  as 
placed  in  one  plane,  that  is, 
without  the  foreshortening  of 

FIG.  i. — Nothodon  lentus  Marsh.     Dia- 
grammatic outline  of  bones  of  top  of  skull,   the     decidedly    convex    profile, 
about  one-half  natural  size.     See,  also,  The  frontal  bones,  very  strong- 

ly  sculptured,  are  broader  and 

thicker  posteriorly,  and  give  articulation  on  their  outer  sides  to  the 
prefrontal  and  postf rental,  which  unite  with  each  other,  excluding 
the  frontal  from  the  margin  of  the  orbit.  The  nasal  bones,  nearly 
as  long  as  the  frontal,  have  the  general  roughening  of  the  skull 
surface,  with  a  single  groove  on  the  upper  side,  obsolete  anteriorly. 
The  prefrontal  is  short,  and  it  extends  but  little  in  front  of  the 
orbit,  articulating  with  the  nasal  and,  more  broadly  on  the  outer 
side,  where  it  curves  downward,  with  the  lachrymal,  which  extends 


res 


KEPT  I  LI  A  :  NOTHODON  19 

forward,  as  in  other  Cotylosauria,  to  form  the  posterior  border  of 
the  nares.1 

The  postfrontal,  a  short  and  thick  bone  like  the  prefrontal,  has 
a  thickened  sutural  border  posteriorly  for  the  postorbital.  The 
parietals  are  rather  small  bones,  touching  each  other  for  a  short 
distance  only  in  front  and  behind  the  "enormous"  parietal  fora- 
men. In  front  they  articulate  by  a  broad,  underlapping  squamous 
suture  with  the  frontal,  on  the  outer  side  with  the  postfrontals 
and  postorbitals,  and  with  another  element  perhaps  between  them 
and  what  I  here  call  the  squamosals.  Back  of  the  parietals 
are  the  broad  dermoccipitals,  which  are  blended  on  the  upper 
side  with  the  supraoccipitals  almost  indistinguishably.  I  believe, 
however,  that  their  sutural  separation  follows  about  the  line  as 
I  have  drawn  it.  On  the  under  side,  the  cartilage  supraoccipital 
forms  the  whole  of  the  superior  surface  of  the  brain  chamber 
posteriorly  and  on  either  side  includes  more  or  less  of  the  semi- 
circular canals  and  otic  cavity.  The  brain  surface  runs  upward 
and  forward,  in  one  specimen  narrowing  into  a  groove  which  leads 
into  the  pineal  chamber;  in  the  other  specimen  the  anterior 
part  of  the  groove  has  been  broken  away  cleanly  from  the  suture 
connecting  the  supraoccipital  with  the  dermoccipital.  It  is  clear 
that  the  supraoccipitals  met  the  parietals  in  the  middle,  wholly 
excluding  the  dermoccipital  from  contact  with  the  brain.  The 
pineal  opening,  as  has  been  said,  is  enormously  large,  twenty- 
three  millimeters  in  longitudinal  diameter,  by  about  twenty  in  the 
transverse  diameter.  Its  walls  are  seven  millimeters  in  height, 
vertical  throughout  the  thickness  of  the  roof  bone,  with  sharp  and 
rather  protuberant  edges  below,  save  where  the  cavity  continues 
back  into  the  narrowed  brain  roof  of  the  supraoccipital  bone. 

1 1  have  for  several  years  been  much  inclined  to  accept  the  conclusion  reached  by 
Jaekel  that  the  real  lachrymal  of  the  reptiles  is  homologous  with  the  so-called  pre- 
frontal of  the  reptiles  and  amphibians,  but  have  been  loath  to  accept  the  name  proposed 
for  the  so-called  lachrymal  by  Jaekel,  "postnarial."  Gaupp's  more  recent  researches 
seem  to  prove  the  contention  of  Jaekel,  but  I  am  not  at  all  inclined  to  accept  the  name 
proposed  by  Gaupp  for  the  bone,  "adlachrymal,"  in  lieu  of  Jaekel's  name.  In  the  primi- 
tive condition  of  the  bone  it  does  not  enter  into  the  formation  of  the  orbit  at  all,  but 
forms  a  part  of  the  posterior  border  of  the  nares,  so  that  objection  to  the  term  "post- 
narial" is  not  pertinent  on  the  grounds  of  its  position,  though  remote  from  the  nares  in 
the  higher  forms.  Xor  can  I  see  why  the  term  "adlachrymal"  is  any  more  appropriate. 


20  AMERICAN  PERMIAN  VERTEBRATES 

Among  other  vertebrates  I  know  of  nothing  to  compare  with  this 
condition  of  the  pineal  vacuity,  unless  it  be  Casea;  that  the 
chamber  lodged  some  part  of  the  brain  substance  there  would  seem 
to  be  no  doubt,  possibly  a  part  of  the  mesencephalon ;  if  it  lodged 
the  pineal  body  only  then  it  would  seem  very  probable  that  the 
organ  was  functional.  The  surface  of  the  parietal  and  frontal 
bones  on  either  side  of  the  brain  surface  and  pineal  chamber  is 
entirely  smooth,  with  no  indications  for  sutural  attachment  of  the 
descending  plates  described  by  Case. 

Among  the  material  acquired  later  there  is  a  quadrate  bone, 
but  so  very  different  in  structure  from  that  of  either  the  Pariotichidae 
or  Pelycosauria  that  I  cannot  understand  it. 

Of  the  limb  bones  I  find  four,  all  rather  closely  associated  with 
the  type,  and  doubtless  the  ones  referred  to  by  Marsh  in  his  original 
description.  They  agree  so  closely  in  size  and  appearance  that  it 
is  very  probable  they  belonged  to  the  one  individual  and  that  prob- 
ably the  type  of  the  genus  and  species.  I  find  no  others  in  the 
collections  which  I  can  refer  positively  to  Nothodon,  though  a 
fragmentary  femur  and  a  fragmentary  humerus  may  belong  here. 
The  bones  preserved  are  quite  characteristic  of  the  Diadectidae 
short,  heavy,  and  stout.  The  left  tibia,  shown  in  Plate  XXXV; 
Fig.  i,  is  a  very  stout,  short  bone;  its  outer  border  is  deeply  con- 
cave and  rather  thin,  less  so  than  the  inner  and  less  thickened; 
the  distal  articular  surface  is  crescentic  in  outline,  the  inner  horn 
the  thinner;  the  ventral  surface  is  more  deeply  concave  than  the 
dorsal;  the  shape  of  the  proximal  articular  surface  is  shown  in  the 
plate. 

The  left  fibula  (Plate  XXXV,  Fig.  2)  has  the  upper  articular 
surface  oblique,  and  the  lower  end  is  much  expanded;  there  is  a 
marked  protuberance  near  the  outer  distal  border;  it  seems  to  be 
normal. 

The  left  radius  and  the  left  ulna  (Plate  XXXV)  from  their 
association  may  belong  in  the  same  forearm.  The  radius  is  nearly 
symmetrical  in  shape,  the  lower  extremity  a  little  more  expanded 
than  the  upper;  the  upper  articular  surface,  somewhat  compressed, 
is  sub  triangular  in  shape;  the  lower  transversely  oval;  its  inner 
border  is  a  little  thinner  and  a  little  more  deeply  concave  than  the 


KEPT  I  LI  A:  NOTHODON  21 

outer.  The  sigmoid  fossa  of  the  ulna  is  large  and  concave;  evi- 
dently the  humerus  has  a  considerable  trochlear  surface;  the  olec- 
ranon  is  not  much  produced,  and  was  largely  cartilaginous;  near 
the  extremity  on  the  outer  side  there  is  a  stout  rugosity  for  mus- 
cular attachment.  The  radial  border  is  deeply  concave  and  stout; 
the  inner  border  is  thin  and  nearly  straight.  The  distal  extremity 
is  considerably  expanded,  thick  and  angular  on  the  radial  side, 
thinner  and  rounded  at  the  inner  angle;  doubtless  a  pisiform  articu- 
lated hera  Marsh  speaks  of  an  ossified  carpus  and  tarsus.  Among 
the  numerous  carpal  bones  there  is  none  which  I  can  positively 
refer  to  Nothodon.  The  lingual  phalange  shown  in  Plate  XXXIV 
may  belong  with  Nothodon,  but  since  Eryops  has  similar  ungual 
phalanges  it  may  belong  in  that  genus. 

There  are  numerous  vertebrae  in  the  collection  from  different 
parts  of  the  column  which  in  much  probability  belong  with 
Nothodon.  For  the  most  part  the  arches  are  separate,  or  have  been 
so  broken  into  fragments  and  dispersed  that  only  a  few  have  been 
restored  to  anything  near  completeness.  The  spine  is  stout,  with 
a  thick  upper  extremity  (Plate  XXXVI,  Fig.  2),  convex  above 
and  not  much  longer  than  broad;  on  each  side  above  there  is  a 
ribbed  thickening  in  the  middle.  The  zygapophyses  are  rather 
stout,  but  there  is  no  vestige  of  a  hyposphene,  so  characteristic  of 
Diadectes.  The  articular  surface  for  the  capitulum  forms  a  dis- 
tinct facet  just  back  of  the  front  margin  of  the  centrum,  and  very 
low  down.  In  this  vertebra  there  is  a  small  hypopophysial  pro- 
tuberance in  the  middle  below  and  between  the  two  capitular  facets 
that  reminds  one  of  Elcobrosaurus  Case.  The  centrum  has  a  high 
and  thin  keel  in  the  middle.  The  diapophyses  were  evidently  of 
moderate  length,  but  broken  off  in  the  specimen  figured. 

The  type  of  vertebra  described  is  very  unlike  that  characteristic 
of  the  species  of  Diadectes  from  Texas,  which  resembles  more  the 
pariotichid  type  than  the  pelycosaurian,  as  does  this.  That  these 
vertebrae  belong  with  either  Sphenacodon  or  Ophiacodon  seems 
improbable,  since  no  known  forms  of  that  group  have  elongated 
thickened  spines;  furthermore,  the  much  greater  number  of  verte- 
brae of  the  pelycosaurian  type  in  the  collection  agrees  better  with 
the  preponderance  of  skeleton  and  skull  bones  of  the  pelycosaurian 
forms. 


22  AMERICAN  PERMIAN  VERTEBRATES 

The  sacral  vertebra  figured  herewith  must  also  be  associated 
with  this  genus.  The  stout  sacral  ribs  are  turned  downward,  and 
their  articulation  is  partly  intercentral. 

So  far  as  the  structure  of  the  skull  is  concerned,  as  also  the  form 
of  the  limb  bones,  so  far  as  they  are  recognized,  there  is  nothing 


FIG.  2. — Nothodon  lentus  Marsh.     Sacral  vertebra,  from  in  front,  natural  size. 

in  this  genus  to  differentiate  it  from  Diadectes,  and  inasmuch  as 
the  name  Diadectes  has  priority  of  ten  days  or  thereabouts  over 
Nothodon  it  must  stand,  and  inasmuch  as  a  family  name  cannot  be 
based  upon  a  synonym,  if  the  two  names  are  synonymous  the 
family  designation  Diadectidae  must  have  precedence,  notwith- 
standing the  priority  of  Nothodontidae.  If,  on  the  other  hand, 


REPTILIA:  LIMNOSCELIS  23 

Nothodon  is  proven  eventually  to  be  a  distinct  genus  from  Diadectes, 
the  family  name  Nothodontidae  Marsh  has  precedence  over  Dia- 
dectidae  Cope. 

Diadectes,  sp. 

In  Plate  XXXIV,  Fig.  8,  is  given  a  photograph  of  an  isolated 
tooth,  showing  the  root,  which  I  refer  somewhat  doubtfully  to  a 
small  species  of  this  genus.  It  was  found  associated  with  a  very 
large  species  of  Diadectes  in  the  Craddock  bone-bed. 

Family  Limnoscelidae 

Williston,  American  Journal  of  Science,  XXXI,  380,  May,  1911. 

Allied  to  the  Diadectidae,  but  the  mandibular  and  maxillary 
teeth  are  elongate  conical,  those  of  the  premaxillary  very  long, 
and  three  in  number  on  each  side;  skull  nearly  smooth,  elongate, 
depressed;  no  otic  emargination;  parietal  foramen  small;  a  single 
sacral  vertebra;  carpus  and  tarsus  incompletely  ossified;  no 
hyposphene. 

LIMNOSCELIS 

Williston,  American  Journal  of  Science,  XXXI,  380,  May,  1911. 

Limnoscdis  paludis  Williston,  op.  cit.  supra.    New  Mexico. 

The  types  and  only  known  material  of  this  genus  and  species 
are  two  specimens,  preserved  in  the  Yale  Museum,  both  from  the 
same  immediate  locality  in  Rio  Arriba  County,  New  Mexico,  and 
both  inclosed  in  a  like  matrix,  a  rather  dark,  fine-grained  sandstone, 
in  nodular  form.  These  two  specimens  seem  to  be  specifically 
identical,  as  the  slight  differences  observed  between  them  may 
well  be  due  to  age  or  conditions  of  fossilization.  Of  one  of  them 
(No.  809,  Yale  Museum  collections)  there  is  a  nearly  complete 
skeleton,  save  the  skull  and  front  feet  and  a  part  of  one  of  the 
hind  feet;  the  preserved  parts  lie,  for  the  most  part,  in  orderly 
articulation.  The  second  specimen  (No.  811)  is  almost  perfect, 
the  only  missing  parts  that  I  observed  being  the  right  hind  foot,  and 
perhaps  a  part  of  the  left  hind  foot,  both  of  which  had  been  more 


24  AMERICAN  PERMIAN  VERTEBRATES 

or  less  exposed  and  the  bones  somewhat  weathered.  This  skeleton 
lies  in  the  most  orderly  relations,  with  all  its  parts  in  close  articula- 
tion, save  such  as  had  been  disturbed  by  gravitation.  It  is  with- 
out break,  at  least  as  far  as  the  proximal  third  of  the  tail;  some  of 
the  smaller  caudal  vertebrae  may  be  missing,  but,  fortunately,  the 
tail  seems  to  be  quite  complete  in  the  other  specimen.  This  more 
perfect  specimen  (No.  811),  which  may  be  considered  the  type  of 
the  species,  was  found  among  unpacked  material  only  a  few  weeks 
before  my  departure  from  New  Haven  became  necessary,  and  its 
preparation  had  not  been  quite  completed.  When  fully  worked 
out  from  the  matrix  and  prepared  for  exhibition,  it  will  be  one  of 
the  most  notable  specimens  of  a  reptile  ever  obtained  from  the 
Permian  deposits  of  America. 

The  skeleton  is  evidently  that  of  an  animal  which  had  died 
peacefully  in  some  pool  or  body  of  water  undisturbed  by  waves 
or  currents;  nor  does  it  show  any  indications  of  extraneous  forces. 
The  animal  at  death  rested  with  its  ventral  side  downward  upon  a 
hard  bottom,  since  all  the  bones  had  fallen,  so  far  as  was  possible 
with  their  natural  articulations,  to  a  level,  as  is  the  case  with  fossils 
preserved  in  marine  deposits.  The  skull  and  limbs  are  in  perfect 
articulation,  the  vertebral  column  curved  gently  to  the  left,  the 
pectoral  and  pelvic  girdles  intact  and  in  position,  and  with  all  the 
bones  of  the  limbs  closely  articulated,  so  far  as  they  are  preserved, 
at  least,  save  a  few  of  the  terminal  phalanges.  The  sacral  vertebra 
is  attached  to  the  ilia,  but  the  vertebrae  immediately  preceding 
and  succeeding  it  had  fallen  to  the  level  of  the  pubes  and  ischia. 
As  the  specimen  lies  in  place  it  measures  three  feet  four  inches  to 
the  hind  end  of  the  ischia,  while  the  articulated  or  nearly  articulated 
tail  of  No.  809  has  a  length  of  forty  inches  to  where  the  centra  meas- 
ure ten  millimeters  in  diameter.  Yet  smaller,  unarticulated  verte- 
brae among  the  unassociated  material  indicate  a  possible  length  of 
the  tail  of  forty-four  or  forty-five  inches,  or  a  total  length  for  the 
the  skeleton  of  about  eighty-four  inches. 

Skull. — The  skull  of  Limnoscelis  paludis  is  remarkable  in  many 
respects,  and  fortunately  this  part  of  the  specimen  which  serves 
as  the  type  is  noteworthy  for  its  completeness  and  perfection  of 
preservation.  Like  the  remainder  of  the  skeleton,  with  which  it 


REPTILIA:  LIMNOSCELIS  25 

was  in  close  articulation,  it  lay  upon  its  ventral  side,  slightly  de- 
pressed by  its  own  weight  in  fossilization,  and  a  little  skewed  to  the 
right.  As  collected,  it  was  broken  in  eight  or  ten  pieces,  the  bone 
so  firm  that  it  permits  the  matrix  to  be  removed  very  completely, 
which  has  been  done  by  the  skilful  head  preparator  of  the  Yale 
Museum,  Mr.  Hugh  Gibbs;  not  quite  completely  yet,  the  anterior 
palatal  region  being  still  invisible.  Since  the  mandibles  are  clearly 
in  natural  relations  with  each  other,  save  for  the  slight  twisting, 
and  the  upper  part  of  the  skull  is  undisturbed,  the  obliquity  has 
been  corrected  in  the  drawings — a  matter  of  no  difficulty.  In  a 
future  paper  a  restoration  of  the  skeleton  will  be  given.  Some 
facts  of  interest,  especially  the  number  and  shape  of  the  mandibular 
and  maxillary  teeth,  were  made  out  from  the  separated  pieces  be- 
fore they  were  cemented  together,  characters  which  will  again 
become  visible  when  the  preparation  of  the  skull  is  completed. 
The  surface  of  the  skull  is  almost  smooth  with  feeble  indications  of 
small  pits. 

The  skull  of  Limnoscelis  is  remarkable  among  terrestrial  rep- 
tiles for  its  elongated  form  and  highly  developed  incisor  teeth. 
The  upper  surface  is  nearly  in  one  plane  from  the  margin  of  the 
occiput  to  near  the  extremity  of  the  rostrum,  somewhat  convex 
above  in  front  of  the  eyes,  and  the  parietal  region  is  moderately 
convex  on  the  sides.  Fortunately  the  sutures  of  the  skull  nearly 
everywhere  are  quite  distinct,  even  visible  in  the  photograph  as 
serrated  or  zig-zag  lines.  A  few  cracks  are  present,  but  they 
are  not  confusing  save  in  a  few  cases,  but  those  are  in  the  most 
important  part  of  the  skull,  the  posterior  temporal  and  occipital 
region.  The  sides  of  the  skull,  with  the  mandibles  in  place,  are 
of  nearly  uniform  height,  that  at  the  nostrils  being  quite  what 
it  is  at  the  temporal  region,  unless  there  has  been  a  slight  depres- 
sion in  the  latter  place.  From  just  in  front  of  the  orbits  the  skull 
widens  very  rapidly,  the  orbits  themselves  being  nearly  wholly 
concealed  in  top  view  by  the  overhanging  roof  of  the  skull.  In 
front  of  the  orbits  there  is  a  rather  deep  depression  on  each  side. 
Back  of  the  orbits  there  seems  to  have  been  a  nearly  vertical  wall 
for  some  distance,  and  then  convex  bioadly  outward.  The  nares 
are  of  considerable  size,  oval  in  shape,  and  situated  close  to  the 


26  AMERICAN  PERMIAN  VERTEBRATES 

anterior  end  of  the  skull.  The  orbits  are  relatively  small  and 
situated  far  back,  the  distance  between  orbits  and  nares  being 
greater  than  the  extent  of  the  skull  posteriorly.  They  are  oval 
in  outline,  somewhat  narrowed  in  the  specimen,  their  planes  nearly 


FIG.  3. — Limnoscelis  paludis  Will.  Skull  from  above,  two-fifths  natural  size. 
pm,  premaxilla;  n,  nasal;  /,  lachrymal;  /,  frontal;  pf,  prefrontal;  pof,  postfrontal; 
po,  postorbital;  pa,  parietal;  do,  dermoccipital;  t,  tabulare. 

parallel  to  each  other  and  nearly  vertical,  the  posterior  part  turned 
a  little  outward. 

The  premaxillae  are  very  massive  bones,  strongly  protuberant 
in  front.  The  suture  uniting  them  with  the  nasal  is  strongly 
digitative,  beginning  at  the  front  end  of  the  nares.  Each  pre- 
maxilla has  three  large,  conical,  and  recurved  teeth.  In  the  specimen 


KEPT  I  LI  A:  LIMNOSCELIS  27 

the  interior  one  on  the  right  side  had  been  lost  before  fossilization, 
but  its  mate  is  complete;  the  second  and  third  teeth  are  succes- 
sively smaller,  but  of  the  same  character  as  the  inner  one,  long, 
conical,  and  recurved.  The  bases  of  two  are  present  on  one  side, 
with  indications  in  the  matrix  of  their  length.  Doubtless  when  the 
skull  is  finally  prepared  the  missing  parts  will  be  found.  The 
long  tooth  lies  in  the  specimen  as  I  have  figured  it,  directed  down- 
ward and  backward,  and  closely  applied  to  the  end  of  the  mandible. 
The  maxilla  has  quite  the  same  relations  as  in  the  other  Ameri- 
can cotylosaurs  where  it  is  known,  a  rather  narrow  bone  united 
with  the  premaxilla  below  the  nares,  with  the  lachrymal  through- 
out nearly  its  whole  length  above,  and  with  the  jugal  posteriorly 
below  the  orbit,  which  it  joins  by  a  long,  oblique,  serrated  suture. 
The  precise  number  of  teeth  I  cannot  be  sure  of.  On  the  left  side 
the  teeth  are  hidden  by  the  obliquely  compressed  mandibles  from 
the  outer  side;  on  the  right  they  are  not  perfect.  Before  the  parts 
were  cemented  together,  Mr.  Gibb  worked  out  the  left  maxillary 
and  mandibular  teeth  from  the  inner  side  in  large  part,  and  these 
have  been  used  to  complete  the  figures  in  the  drawing.  There  are 
at  least  twenty  in  the  maxilla,  and  perhaps  more.  The  anterior 
ones  are  longer  and  stouter,  conical  like  the  incisors,  and  somewhat 
recurved.  Their  attachment  to  the  bone  is  more  or  less  pleuro- 
dont.  The  posterior  teeth  are  shorter,  but  are  also  nearly  circu- 
lar at  their  bases.  There  is  but  one  row.  The  nasals  are  very 
large  bones,  occupying  nearly  the  whole  of  the  upper  surface  of 
the  skull  in  front  of  the  orbits,  and  are  gently  convex  or  flat.  The 
lachrymals,  as  in  probably  all  Cotylosaurians,  are  elongate,  form- 
ing the  posterior  border  of  the  nares  and  a  part  of  the  anterior 
border  of  the  orbits.  As  in  the  Diadectidae,  and  quite  unlike  the 
condition  in  the  Pariotichidae,  the  small  frontals  do  not  take  any 
part  in  the  orbital  border,  which  is  formed  by  the  prefrontals  and 
postf rentals;  as  in  the  Diadectidae,  both  these  bones  are  short 
and  broad,  reaching  scarcely  beyond  the  orbit  in  front  or  behind. 
The  parietals  are  short,  broad  bones  forming  most  of  the  superior 
surface  of  the  skull  back  of  the  orbits;  the  parietal  foramen  is  of 
the  usual  size,  very  unlike  the  enormous  one  of  the  Diadectidae. 
The  sides  of  the  skull  back  of  the  orbit  are  formed  chiefly  by  the 


28  AMERICAN  PERMIAN  VERTEBRATES 

squamosal,  very  clearly  distinct  from  the  small  quadra  to  jugal 
on  the  lower  posterior  margin,  but  not  distinguishable  at  present 
from  the  postorbitals  and  epiotics  quite  to  my  satisfaction.  Back 
of  the  parietals  are  the  narrow  transverse  dermoccipitals,  which 
seem  to  be  quite  distinct  from  a  small  bone  at  the  outer  angle, 
which  doubtless  is  the  tabulare  (epiotic).  The  structure  of  the 
posterior  part,  the  occipital  region,  is  somewhat  confusing,  and 
I  do  not  feel  at  all  sure  of  my  determinations.  The  discussion 
of  this  region  I  reserve  for  a  later  paper,  hoping  that  additional 
material  may  be  forthcoming.  The  structure  of  the  palate,  so 
far  as  it  has  been  developed  in  the  specimen,  is  most  interesting, 
so  closely  resembling  the  "  rhynchocephalian "  type  that  a  few 
years  ago,  had  it  been  found  without  other  parts  of  the  skull,  it 
would  have  unhesitatingly  been  located  in  the  "Diapsida"  and 
"Diaptosauria."  The  specimen  has  not  yet  been  thoroughly 
cleaned  in  the  anterior  part,  so  that  I  can  say  nothing  of  the  vomers. 
The  palatines  and  united  pterygoids  are,  as  in  Labidosaurus  and 
Pariotichus,  separated  by  a  more  or  less  elongated  interpterygoidal 
space.  The  eminence  in  the  region  of  the  transverse,  if  the  bone 
be  distinct,  as  I  think  it  is,  is  crowned  by  a  row  of  five  or  six  teeth, 
evidently  more  or  less  conical  in  life,  but  unpreservable  in  the 
preparation  of  the  skull.  In  front  of  these  teeth  I  can  find  evidence 
of  but  a  single  tooth,  located  as  I  have  marked;  I  am  not  quite 
sure  of  it,  but  in  all  probability  there  were  others.  Opposite  the 
front  end  of  the  basisphenoid,  the  pterygoid  on  each  side  articulates 
with  a  stout  basipterygoid  process  of  the  basisphenoid,  quite  as 
in  the  lacertilians,  the  first  evidence  I  have  seen  among  the  Permian 
vertebrates  of  a  real  articulation  at  this  place.  The  pterygoid  has 
a  pit  or  depression  on  the  inner  side  for  the  head  of  this  large  pro- 
cess. Back  of  these  processes  the  pterygoids  resemble  remarkably 
the  like  processes  of  the  lizards,  a  not  very  wide,  rather  stout, 
obliquely  placed  process  reaching  backward  to  articulate  with  the 
lower  inner  side  of  the  quadrate.  In  the  middle  the  large  basisphe- 
noid is  conspicuous;  unlike  that  of  the  Diadectidae  it  is  stout  and 
rounded  below,  where  it  gives  off  the  basipterygoid  processes. 
Anteriorly  it  gives  off  the  so-called  parasphenoid.  But  the  "  para- 
sphenoid"  in  this  case  is  a  thin  vertical  plate,  thickened  poste- 


REPTILIA:  LIMNOSCELIS 


29 


riorly  to  join  the  anterior  end  of  the  basisphenoid,  very  much 
as  in  Trinacromerum  among  the  plesiosaurs.  In  the  specimen  the 
front  part  lies  obliquely  in  the  matrix  an  inch  or  more  in  width, 
with  the  lower  margin,  that  visible  in  its  normal  position,  narrow. 
Behind  the  rounded  median  convexity  of  the  sphenoid,  the  bone 


FIG.  4. — Limnoscelis  paludis.     Skull,  from  below,  two-fifths  natural  size,     sp, 
splenial;  pa,  prearticular;  st,  stapes  (?). 

is  broadly  concave  in  the  middle,  on  either  side  of  which  the  usual 
basisphenoid  process  is  directed  downward,  backward,  and  outward, 
to  end  in  a  rather  stout  projection.  In  the  middle  of  this  concavity 
the  sutural  line  for  union  with  the  basioccipital  is  evident.  The 
occipital  condyle  is  quite  flat  or  even  concave,  as  in  Diadectes  and 


30  AMERICAN  PERMIAN  VERTEBRATES 

Pareiasaurus,  a  strong  indication  of  relationship.  On  either 
side  of  the  basioccipital  I  think  I  have  interpreted  the  bones  of  the 
posterior  palatal  and  occipital  regions,  but  I  prefer  to  wait  before 
publishing  my  conclusions,  in  the  hope  of  getting  additional  material 
of  this  form  the  coming  season. 

The  mandibles  of  Limnoscelis  are  very  powerful,  indicative  of 
the  carnivorous  habits  of  the  animal  in  life.  They  lie  in  perfect 
relation  to  each  other,  save  that  they  are  a  little  skewed  to  the 
right.  They  are  broadly  separated  behind,  with  a  long  convexity 
on  the  sides,  and  again  expanded  at  the  front  end.  The  teeth  are 
only  partly  visible  from  without;  the  one  or  more  large  ones  in 
front  opposing  the  premaxillary  teeth  is  wholly  hidden;  nor  can 


FIG.  5. — Limnoscelis  paludis.  Skull,  from  side,  two-fifths  natural  size,  pm, 
premaxilla;  n,  nasal;  /,  lachrymal;  m,  maxilla;  />/,  pref rental;  pof,  postfrontal; 
po,  postorbital;  j,  jugal;  sq,  squamosal;  gj,  quadratojugal;  q,  quadrate;  d,  dentary; 
sur,  surangular;  ang,  angular. 

the  number  be  made  out  with  certainty.  The  postarticular 
process  is  small,  not  extending  back  of  the  quadrate,  or  if  so, 
for  a  few  millimeters  only.  Externally  the  suture  separating 
the  angular  from  the  surangular  passes  forward  near  the  upper  part 
of  the  bone,  and  backward  nearly  to  the  extremity.  On  the  inner 
side  of  the  mandible  the  structure  is  peculiar.  A  broad  flange  is 
directed  inward,  nearly  vertically,  opposite  the  middle  of  the 
articular  surface,  concave  in  front.  The  suture  separating  the 
prearticular  from  the  articular  is  very  conspicuous,  passing  back 
over  the  flange.  In  front  the  prearticular  passes  far  forward, 
between  the  upper  opening  to  the  cavity  of  mandible  and  the 


REPTILIA:  LIMNOSCELIS  31 

elongated  opening  of  MeckePs  groove  near  the  middle  of  the  inner 
side,  before  the  middle  of  the  bone  antero-posteriorly .  A  fracture  of 
the  mandible  a  little  in  front  of  the  articular  shows  a  large  cavity 
with  an  elongated  opening  above  back  of  the  teeth.  The  elongated 
vacuity  is  bounded  by  the  angular  below,  by  the  splenial  in  front. 


FIG.  6. — Limnoscelis  paludis.     Outline  of  back  of  skull,  two-fifths  natural  size. 


FIG.  7. — Inner  sides  of  mandibles,  one-half  natural  size.  A,  Limnoscelis  palndis; 
B,  Labidosaurns  hamatus.  art,  articular;  q,  quadrate;  sur,  surangular;  cor,  coro- 
noid;  pa,  prearticular;  ang,  angular;  sp,  splenial. 

by  the  prearticular  above  behind,  anteriorly  apparently  by  the 
coronoid ;  it  is  evidently  merely  the  exposed  groove.  The  splenial 
is  very  broadly  visible  on  the  under  side  of  the  mandible,  the 
suture  between  it  and  the  dentary  beginning  some  distance  in 
front  of  the  posterior  end  of  the  median  symphysis,  and  extending 


32  AMERICAN  PERMIAN  VERTEBRATES 

back  nearly  as  far  as  the  posterior  end  of  the  internal  vacuity. 
On  one  side  a  piece  about  two  inches  in  extent  of  this  bone  has 
been  peeled  off  from  the  dentary,  showing  the  bone  to  be  thin, 
not  more  than  six  or  eight  millimeters  in  thickness.  In  front, 
the  splenial  turns  upward  to  cover  the  inner  side  of  the  mandible 
below  the  teeth,  covering  the  groove  for  Meckel's  cartilage  ante- 
riorly. Interesting  is  the  fact  that  the  existence  of  a  separate 
prearticular  bone  is  demonstrated  beyond  doubt  in  this  genus, 
and  also  that  the  splenials  meet  in  a  median  anterior  symphysis 
as  in  Labidosaurus,  the  early  long- snouted  crocodiles,  Plesiosauria, 
etc.  I  give  herewith  a  figure  of  the  inner  side  of  the  mandible  of 
Labidosaurus,  showing  a  very  similar  arrangement  of  all  the  bones ; 
the  suture  separating  the  prearticular  from  the  articular  is  very 
evident  in  part,  if  not  all  its  course. 

The  separate  prearticular  bone  is  evidently  characteristic 
of  the  Cotylosauria  if  not  all  the  early  reptiles  and  amphibians. 
I  have,  I  think,  demonstrated  its  existence  in  the  Plesiosauria, 
though  Andrews,  in  his  latest  paper  on  the  plesiosaurian  mandible,1 
has  not  distinguished  the  suture  separating  it  from  the  splenial. 
The  prearticular,  with  the  same  relations  as  those  of  the  plesio- 
saurs  and  cotylosaurs,  is  also  present  in  the  ichthyosaurs,  though 
called  the  coronoid  by  Merriam,  Gilmore,  and  Andrews.  In  all 
cases  it  passes  below  the  large  posterior  opening  of  the  mandible 
for  the  entrance  of  the  nerves,  the  vacuities  below  and  in  front  of 
the  bone  being  for  the  most  part  merely  openings  into  Meckel's 
groove,  as  in  the  crocodiles,  Erpetosuchus  kansensis  Moodie,  etc. 

Vertebrae. — Eighteen  presacral  vertebrae  have  been  cleared 
of  the  matrix,  in  a  continuous  series  curved  to  the  left.  The 
lengths  of  these  vertebrae  are  almost  exactly  the  same  throughout; 
in  front  of  the  exposed  ones  the  vertebrae  above  the  pectoral 
girdle  have  not  yet  been  cleared  of  their  matrix;  the  space  in  which 
they  lie  corresponds  almost  exactly  to  that  of  the  five  vertebrae 
following  them,  and  that  is  probably  the  number  yet  hidden. 
In  front  of  these  the  atlas  and  axis  have  been  partly  exposed, 
giving  twenty-five  as  the  total  number  of  presacral  vertebrae,  two 
more  than  is  known  to  exist  in  Seymouria,  and  probably  two  more 

1  Geological  Magazine,  VIII,  162,  1911. 


R&PTILIA:  LIMNOSCELIS 


33 


FIG.  8. — Limnoscelis  pahidis.  A,  pos- 
terior dorsal  vertebra,  from  behind;  B, 
twenty-second  or  twenty-third  caudal  verte- 
bra, from  the  side;  C,  ulnare. 


than  in  Captor hinus  laticeps  Will.  The  number  in  Limnoscelis  will 
later  be  determined  with  certainty.  The  first  of  the  series  exposed, 
the  eighteenth  presacral,  has  a  shallow  fossa  or  flattened  surface 
below  in  the  middle,  which  fossa  increases  in  depth  posteriorly, 
a  very  characteristic  feature 
which  seems  to  differentiate 
the  genus  from  others  previ- 
ously known,  especially  Dia- 
sparactus  Case.  The  outline 
of  the  centra,  both  on  the 
sides  and  below,  antero-pos- 
teriorly,  is  deeply  concave. 
The  arch  has  a  marked  re- 
semblance to  that  of  Diadectes, 
and,  according  to  Broom,  to 
that  of  Pareiasaurus  also,  and 
is  very  different  from  the  type 
characteristic  of  Labidosaurus 
and  Seymouria.  It  differs  from  that  of  Diadectes  especially  in  the 
absence  of  all  indications  of  a  hyposphene;  but,  if  I  am  correct, 
Nothodon,  which  is  of  course  a  diadectid,  also  lacks  the  hypo- 
sphene, rendering  the 
B  J---1  character  in  conse- 

quence merely  of  ge- 
neric value. 

All  the  observed 
ribs  are  single-headed, 
but  expanded;  that  is, 
without  an  emargi- 
nation  distinguishing 
the  head  from  the  tu- 
bercle. In  Diadectes, 
or  at  least  in  such 
species  as  I  have  been  able  to  study  of  this  genus,  the  ribs  anteriorly 
are  distinctly  double-headed.  The  transverse  processes  are  short 
throughout  the  series,  scarcely  extending  on  the  sides  beyond  the 
margin  of  the  zygapophyses.  This  character  has  been  given  by 


FIG.  9. — Limnoscelis  palndis.  Posterior  dorsal 
vertebra,  one-half  natural  size.  A ,  from  in  front ;  B, 
from  the  side. 


34  AMERICAN  PERMIAN  VERTEBRATES 

Case  as  a  distinctive  one  for  his  genus  Diasparactus,  but,  in  a  large 
species  of  Diadectes  from  Texas  I  do  not  find  any  appreciable  differ- 
ence in  the  prominence  of  the  processes,  at  least  in  the  posterior 
presacral  region.  The  spines  are  moderately  elongate  through  the 
series,  thickened  and  somewhat  rugose  at  the  upper  end.  There  are 
large  intercentra  between  the  centra  below,  and  as  the  vertebrae  lie 
in  the  matrix  a  considerable  space  is  left  between  the  adjacent  verte- 
brae for  cartilage,  indicating  a  very  flexible,  though  not  very  firm 
spinal  column.  The  spines,  of  the  posterior  part  of  the  column  at 
least,  are  about  one  inch  in  length.  The  first  presacral  spine  is  rather 
broad  and  expanded  above,  the  second  and  more  anterior  ones  are 
more  slender.  There  is  but  one  sacral  vertebra,  which  has  a  very 
broad,  stout,  sacral  rib  on  each  side,  turned  directly  downward 
so  as  to  cover  nearly  the  whole  of  the  inner  side  of  the  ilium  at 
its  junction  with  the  ischium  and  pubis,  its  an tero- posterior 
width  being  60  mm.,  its  vertical  width  where  it  joins  the  ilium, 
40  mm.  The  ribs  immediately  in  front  and  behind  are  small  and 
slender  and  do  not  seem  to  touch  the  ilium  at  all.  Case  has 
described  Diadectes  as  having  two  sacral  vertebrae,  but  in  the  speci- 
men in  the  Chicago  collections,  of  a  large  species,  the  structure  of 
the  sacrum  seems  to  be  quite  as  in  Limnoscelis;  and  this  is  also 
the  case  in  a  new  genus  of  Diadectidae,  which  Professor  Case 
will  describe  from  a  specimen  in  the  University  of  Chicago  col- 
lections, collected  by  Mr.  Miller. 

The  first  chevron  occurs  at  the  hind  end  of  the  third  caudal 
vertebra,  the  first  one  visible  above  the  ischia  from  below;  the 
first  three  or  four  of  the  caudal  vertebrae  have  short  free  ribs,  as 
in  other  genera  of  American  Cotylosauria.  The  tail,  as  preserved 
in  specimen  No.  908,  is  rather  slender,  with  short  spines  and 
chevrons,  precluding  the  idea  that  the  animal  was  natatorial  in 
habit.  The  terminal  vertebrae  are  a  little  elongated. 

Pectoral  girdle  and  extremity. — The  pectoral  girdle  lies  in  very 
orderly  arrangement,  with  little  if  any  distortion.  Both  clavicles 
are  in  articulation  with  the  interclavicle,  scapulae,  and  cleithra. 
The  clavicles  have  the  usual  cotylosaurian  form,  curving  under 
the  anterior  end  of  the  interclavicle  and  the  anterior  margin  of  the 
coracoid,  curved  and  somewhat  spoon-shaped  below.  The  long, 


REPTILIA:  LIMNOSCELIS 


35 


dilated,  scapular  part  is  curved  upward  in  a  vertical  plane  and 
obliquely  backward  in  the  articulate  skeleton,  reaching  nearly  to 
the  upper  end  of  the  scapula,  flattened  from  side  to  side  above. 
The  clei thrum  is  small  and  vestigial,  smaller  than  in  Diadectes, 
a  slender,  cylindroid  bone,  reaching  quite  to  the  superior  anterior 
angle  of  the  scapula,  but  not  expanded  over  the  end,  as  in  the 
temnospondyls.  It  is  dilated  at  its  lower  end  to  articulate  with 
the  attenuated  upper  extremity  of  the  clavicle,  lying  between 
the  clavicle  and  the  front  margin  of  the 
scapula.  It  is  only  a  little  more  than 
two  inches  in  length.  The  scapula  is 
very  short.  The  blade  above  is  narrow, 
thinner,  and  curved  outward  on  its  front 
part,  thickened  at  its  posterior  superior 
border.  Its  upper  end  is  truncated,  and 
doubtless  had  a  suprascapular,  carti- 
laginous continuation,  possibly  the  rep- 
resentative unossified  of  the  upper  end 
of  the  clei  thrum.  The  glenoid  fossa  is 
deep  and  large,  the  stout  metacoracoid 
extending  far  back  relatively.  The  pos- 
terior border  of  the  scapula  is  curved 
nearly  uniformly  from  the  angle  to  the 
extremity  of  the  preglenoid  facet,  which 
is  large  and  flattened.  There  is  a  dis- 
tinct supraglenoid  fossa  a  little  below 
the  middle  of  the  bone,  between  the 
borders  which  diverge  near  the  middle 

of  the  length  of  the  scapula ;  it  is  pierced  in  the  usual  temnospondyl 
way  for  the  passage  of  the  supraglenoid  canal.  I  have  observed 
this  foramen  in  this  position  in  scapulae  which  I  refer  to  the  genus 
Ophiacodon,  but  usually  in  the  Pelycosauria  the  opening  pierces 
the  bone  in  front  of  the  scapular  margin.  I  had  supposed  that  this 
foramen  was  characteristic  of  these  old  orders  of  reptiles,  never 
having  seen  any  reference  to  it  in  literature  of  other  orders  of  verte- 
brates. But  I  am  surprised  to  find  that  it  is  quite  typical  of  cer- 
tain lizards,  and  it  perhaps  occurs  in  other  reptiles.  In  the  present 


FIG.  10. — Limnoscelis  pa- 
ludis.  Left  clavicle  and  cleith- 
rum  from  in  front,  two-fifths 
natural  size. 


AMERICAN  PERMIAN  VERTEBRATES 


reptile  I  have  observed  for  the  first  time  in  any  form  other  than  the 
amphibia  the  inner  opening  of  the  foramen  or  canal  back  of  the 
border  of  the  subscapular  fossa,  which  I  have  called  the  glenoid 
foramen.  That  the  canal  perforates  the  bone  to  open  in  the  glenoid 
fossa  I  am  not  prepared  to  affirm.  I  find,  however,  that  the  fora- 
men is  also  present  in  the  Diadectidae,  and  perhaps  in  other  cotylo- 
saurians.  Its  presence  removes  the  last  distinguishing  character 
between  the  temnospondyl  and  cotylosaurian  pectoral  girdles.  One 

may  distinguish  them  now  only  by 
the  smaller  size  of  the  cleithrum 
in  the  reptiles! 

The  suture  separating  the  pos- 
terior coracoid  is  situated  not  far 
back  of  the  supracoracoid  fora- 
men, which  is  unusually  large. 
The  limits  of  the  anterior  cora- 
coid are  not  distinguishable;  the 
bone  is  thinned,  rounded  on  the 
anterior  angle,  which  is  slightly 
underlapped  by  the  clavicle,  and, 
with  the  metacoracoid,  is  curved 
inward  nearly  to  a  horizontal 
plane,  approaching  its  mate  of  the 
opposite  side,  but  separated  by 
the  stem  of  the  interclavicle.  The 
inter  clavicle  reaches  a  little  farther 
back  than  the  hind  angle  of  the 
metacoracoid,  and  is  of  moderate  width;  its  front  part  is  dilated 
and  mostly  hidden  from  view,  as  in  the  other  Permian  reptiles. 

In  each  skeleton  there  is  a  pair  of  bones  found  lying  just  back 
of  the  coracoids,  and  nearly  below  the  vertebrae,  of  the  nature  of 
which  I  am  not  fully  satisfied,  though  there  would  seem  to  be  little 
doubt  but  that  they  are  unusually  large  hyoids  (Plate  XXXVIII, 
Fig.  2).  They  are  about  three  inches  in  length,  greatly  expanded 
on  their  distal,  thin  end,  with  a  somewhat  curved  and  narrowed 
shaft  deeply  concave  in  outline  on  one  side,  less  so  on  the  other, 
thickened  and  truncate  for  articulation  at  the  proximal  end.  The 


FIG.  ii. — Limnoscelis  paludis. 
Interclavicle  and  hyoid,  two-fifths 
natural  size. 


REPTILIA  :  LIMNOSCELIS 


37 


two  bones  in  each  specimen  lie  with  the  thin  ends  nearly  in  apposi- 
tion, as  though  they  had  joined  each  other  in  life. 

Humerus. — The  humerus  is  a  remarkably  short  and  thickset 
bone,  resembling  that  of  Diadectes  more  closely  than  that  of  any 
other  genus  that  I  know.  The  ectocondyle  is  more  expanded  and 
turned  inward  than  in  that  genus,  however,  nor  is  the  proximal 
expansion  so  much  twisted  from  the  plane  of  the  entocondyle  as 
is  the  case  with  the  humeri 
of  more  terrestrial  Permian 
reptiles.  The  entepicondylar 
foramen  is  large,  situated  not 
far  from  the  lower  extremity 
of  the  lateral  process.  The 
ulnar  expansion  is  broad  and 
flat,  and  occupies  a  plane  di- 
vergent from  that  of  the  proxi- 
mal inner  side  of  about  forty- 
five  degrees.  The  capitellum 
is  very  large  and  rounded, 
situated  on  the  outer  angle 
of  the  bone,  as  seen  from  the 
ventral  side,  and  is  remark- 
ably close  to  the  lateral  pro- 
cess. The  ectocondyle  is 
remarkably  stout  and  protu- 
berant, and  is  directed  almost 
rectangularly,  or  even  at  an 
acute  angle  backward,  termi- 
nating very  near  the  middle  of  the  bone  transversely,  and  above  the 
groove  for  the  ulna  on  the  dorsal  side.  It  is  an  interesting  fact 
that  not  only  the  structure  of  the  humerus,  but  also  the  whole 
anterior  limb,  resembles  not  only  that  of  Diadectes,  but  also  that 
of  the  amphibian  Eryops,  suggesting  similar  habits  in  all  three  ani- 
mals, and  possibly,  too,  genetic  affinities.  There  is  a  moderately 
stout  ectepicondylar  process,  as  in  Desmospondylus,  Seymouria, 
Diadectes,  Eryops,  etc.  It  is  situated  a  little  below  the  lateral  pro- 
cess on  the  radial  side. 


FIG.  12. — Limnoscelis  paludis.  Left 
capula,  with  clavicle  and  cleithrum,  two- 
fifths  natural  size,  sc,  scapula;  c,  cleithrum; 
cl,  clavicle. 


38  AMERICAN  PERMIAN  VERTEBRATES 

Radius,  ulna—The  radius  and  ulna  are  very  like  those  of 
Diadectes  and  Eryops,  rather  short  and  stout  bones.  The  two 
lie  in  position  on  each  side,  as  shown  in  the  figure,  the  upper  end 
of  the  radius  partly  lodged  in  the  lower  end  of  the  sigmoid  fossa, 
and  the  two  are  in  one  plane.  The  radius  has  the  capitulum  trun- 
cated and  hollowed  for  articulation  with  the  humerus,  the  extremity 
strongly  convex  on  the  dorsal,  flattened  on  the  ventral  side.  The 
shaft  of  the  bone  is  moderately  narrowed,  and  its  two  borders  are 
nearly  symmetrically  concave.  The  lower  extremity  is  more 
expanded,  with  its  end  truncate  and  flattened  for  articulation  with 
the  radiale  and  intermedium,  the  inner  side  the  thicker.  Just  above 
the  inner  distal  angle  there  is  a  characteristic  protuberance,  which 
evidently  came  in  close  contact  with  the  ulna.  The  ulna  is  a  more 
slender  bone  and  is  a  little  longer;  it  is  thick  and  massive  at  its 
upper  end,  the  shaft  more  slender  than  that  of  the  radius,  and  the 
lower  end  moderately  expanded.  Its  radial  border  is  deeply  con- 
cave, its  inner  border  nearly  straight  to  the  lower  fifth.  The  sig- 
moid fossa  is  deep,  winding  obliquely  about  the  bone,  and  fits 
accurately  the  curved  trochlear  surface  on  the  distal  and  dorsal 
side  of  the  humerus.  Evidently  the  elbow  joint  was  a  strong  and 
firm  one.  The  distal  extremity  of  the  ulna  is  subtruncate,  its 
border  somewhat  oblique  to  that  of  the  radius,  but  with  the  angle 
broadly  rounded  for  articulation  with  the  pisiform.  Both  radius 
and  ulna  have  the  dorsal  side  convex,  the  ventral  more  flattened. 

Front  foot. — Lying  in  close  articulation  with  the  radii  and  ulnae 
are  the  proximal  carpal  bones,  four  in  number  on  each  side,  the 
radiale,  intermedium,  ulnare,  and  pisiform.  The  pisiform  is  a 
small  bone,  thinned  along  its  free  border  and  articulating  in  its 
usual  position  between  the  ulna  and  ulnare.  The  ulnare,  the 
largest  of  the  carpal  elements,  is  an  irregularly  oval  bone,  articulat- 
ing rather  broadly  with  the  ulna  and  the  intermedium,  but  without 
distinct  facets  for  the  other  carpal  elements.  The  smaller  inter- 
medium is  much  thickened,  articulating  with  the  ulna,  ulnare, 
and  the  radius,  with  a  very  small  free  border  between  the  ulna 
and  the  radius.  The  radiale  is  the  smallest  of  the  three,  almost 
vestigial  in  fact,  elongate,  ovate  in  shape,  with  the  radial  border 
straight  and  flattened,  the  outer  end  obtusely  pointed;  it  merely 


REPTILIA  :   LIMNOSCELIS 


39 


touches  the  intermedium.  The  ventral  surface  of  all  three  of  these 
bones  is  flattened,  the  dorsal  more  rounded,  that  of  the  radiale 
obsolete.  Especially  remarkable  is  the  fact  that  all  of  these  proxi- 
mal carpal  bones  save 
the  pisiform  are  very 
small,  smaller  than  in 
Diadectes  even,  and 
much  smaller  than  in 
other  known  Permian 
reptiles. 

The  remaining  bones 
of  the  right  foot  were 
found  nearly  all  con- 
nected, for  the  most 
part  in  the  relations  of 
the  living  animal.  The 
foot  had  been  slightly 
twisted  in  fossilization, 
disturbing  somewhat 
the  relations  of  the 
metapodials.  Of  the 
phalanges  all  were  found 
in  association  save  two 
terminal  ones,  the  distal 
phalanges  somewhat 
confused  in  the  three 
middle  fingers.  The 
three  distal  carpal  bones 
were  found  in  the  posi- 
tions shown  in  the  fig- 
ure, but  there  were  no 
traces  of  others,  and 
they  could  have  hardly 
escaped  notice  had  they 
been  fossilized  with  the  others.  Evidently  these  nodular  bones 
represent  the  centrale  and  the  third  and  fourth  carpalia.  Fortu- 
nately the  bones  of  the  left  foot  were  found  in  the  matrix  in  as 


V 


IV 


III 


FIG.  13. — Limnoscelis  paludis.  Right  front 
leg,  dorsal  side,  two-fifths  natural  size,  re,  radiale; 
?',  intermedium;  ue,  ulnare;  p,  pisiform;  I-V,  first- 
fifth  digits. 


40  AMERICAN  PERMIAN  VERTEBRATES 

natural  relations  as  one  could  wish,  and  they  will  be  so  retained  in 
the  prepared  skeleton.  The  block  containing  the  distal  carpal s 
and  the  digital  bones  had  been  separated  in  collection  from  that 
containing  the  forearm  and  proximal  carpals,  and  was  not  accu- 
rately readjusted.  The  three  carpal  nodules  are  quite  as  in  the 
other  hand  with  no  traces  of  others;  from  which  facts  I  have  no 
doubt  that  they  were  the  only  ones  ossified,  and  they  but  imper- 
fectly. Of  the  digits  the  bones  of  the  three  middle  toes  were  all 
in  perfect  articulation  save  the  ungual  phalanges  of  the  second  and 
fourth  digits,  which  are  missing.  Of  the  first  digit,  the  ungual 
phalange  is  displaced  and  the  phalanges  of  the  fifth  have  not  been 
adjusted  to  the  metatarsal.  However,  these  digits  were  preserved 
in  perfect  articulation  in  the  right  foot.  From  these  facts,  which 
I  have  given  in  detail  because  of  their  importance,  it  is  certain 
that  the  phalangeal  formula  is,  as  is  seen,  2,  3,  4,  5,  3,  fixing  for 
the  first  time  the  foot  structure  in  an  American  cotylosaurian,  and 
save  for  Procolophon,  in  any  member  of  the  order.  My  figure  was 
made  by  simply  tracing  the  outlines  of  the  various  bones  as  they 
lie  in  position  and  transferring  them.  The  only  doubt  that 
remains  is  the  precise  width  of  the  space  I  have  left  for  the  carpal 
elements;  it  may  be  a  trifle  too  broad.  As  is  seen,  the  foot  is 
remarkably  broad  and  flat,  lying  in  the  matrix  in  nearly  one 
plane,  with  the  phalanges  short,  the  ungual  ones  broad  and  hoof- 
like  as  in  Diadectes,  and  probably  also  Eryops.  The  foot 
resembles  that  of  Diadectes  somewhat,  save  that  the  proximal 
carpal  bones  are  large,  and  the  distal  row  seems  to  be  fully  ossified 
in  that  genus. 

Three  years  ago  I  expressed  the  opinion  that  the  phalangeal 
formula  2,  3,  4,  5,  3  (4)  was  the  primitive  one  for  land  reptiles,  if 
not  for  land  vertebrates,  as  observed  in  Eosauravus  copei.  Broom 
is  of  the  opinion  that  this  is  the  formula  in  Propappus  and  he  has 
proven  it  to  be  that  of  Procolophon.  Dromopus  agilis  Marsh,  as 
figured  by  the  author  and  Matthew,  shows  a  similar  phalangeal 
formula.  These  footprints  are  from  near  the  upper  part  of  the 
coal  measures  in  the  vicinity  of  Osage,  Kansas.  Marsh  thought 
that  they  were  made  by  a  lacertilian  rather  than  an  amphibian, 
a  natural  error  considering  the  lacertilian  form  of  the  prints. 


KEPT  I  LI  A  :  LIMNOSCELIS  41 

They  probably  come  from  some  microsaurian  reptile  not  unlike 
Eosauravus  copei. 

Pelvic  girdle  and  extremity. — The  pelvic  girdle  lies  in  natural 
articulation,  with  but  little  disturbance;  the  right  pubis  is  a  trifle 
compressed,  and  the  extremity  of  the  left  ilium  had  been  broken 


FIG.  14. — Limnoscelis  paludis.     Pelvis,  from  below,  two-fifths  natural  size,     a, 
cross-section  through  pubes  at  a;  b,  cross-section  through  ischia  at  b. 

off  and  turned  aside  before  fossilization.  Both  femora  are  closely 
articulated  in  the  acetabula,  directed  obliquely  dorsad  and  cephalad. 
The  pubes  and  ischia  lie  in  a  subhorizontal  position,  with  a  pro- 
tuberant carina  along  the  middle,  deeper  anteriorly.  This  keel, 
however,  is  not  formed  by  the  downward  deflection  of  the  margin 
of  the  bones,  but  by  the  increased  depth  of  the  symphysis,  as  will  be 
seen  from  the  cross-sections  of  the  figure,  sections  made  at  points 


AMERICAN  PERMIAN  VERTEBRATES 


of  fracture  in  the  specimen.  The  ischia  have  an  angular  margina- 
tion  in  the  middle,  the  sides  curving  outward  and  upward  to  the 
rounded  posterior  angle.  The  sutural  division  between  ischium 
and  pubis  is  at  about  two-fifths  of  the  length  from  the  front  end 
of  the  pelvis.  The  pubic  foramen  is  remarkably  large  at  the 
bottom  of  a  rather  deep  fossa  situated  a  little  in  front  of  the 
ischio-pubic  suture,  and  not  far  from  the  acetabular  border.  The 
acetabulum  is  deep  and  large,  with  an  overhanging,  nearly  hori- 
zontal roof-like  process,  at  the  upper  posterior  part.  In  life  the 

cavity  looked  almost  di- 
rectly outward.  The  ilium 
is  relatively  small ;  it  is  flat- 
tened and  thinned  above 
and  in  front,  with  a  rather 
stout,  narrow  process  di- 
rected backward  and  a 
little  outward,  nearly  hori- 
zontal. Upon  the  whole, 
the  structure  of  the  pelvis 
is  nearly  identical  with 
that  of  Diadectes  and  the 
Pariotichidae,  and  even  of 
Eryops  and  Cacops,  save  in 
the  form  of  the  ilium;  in 
Diadectes,  broader  above 
and  produced  backward; 
in  the  temnospondyls  without  iliac  projections  either  in  front  or 
behind.  While  there  is  but  a  single  sacral  vertebra  in  Limnoscelis 
and  Seymouria,  in  Cacops  there  are  two,  a  precise  reverse  of  what 
has  often  been  supposed  to  be  diagnostic  characters  of  these  two 
classes  of  vertebrates.  The  femur  is  of  the  characteristic  Diadectes 
type,  short,  stout,  and  expanded,  with  a  heavy,  protuberant  tro- 
chanter,  and  a  large  digital  fossa.  The  trochanter  has  a  large  facet, 
20  or  more  millimeters  in  diameter,  looking  backward,  and  is 
rugose;  the  adductor  ridge  is  pronounced  and  oblique.  The  tibia, 
like  the  femur,  is  short  and  stout,  with  a  greatly  expanded  upper 
end,  and  a  strong  cnemial  protuberance.  The  outer  side  is  deeply 


FIG.  15. — Limnoscelis  paludis.  Diagram  of 
pelvis,  from  the  side,  il,  ilium;  pb,  pubis;  is, 
ischium. 


REPTILIA:  LIMNOSCELIS 


43 


concave  in  outline,  the  inner  less  so.     The  lower  extremity  is  much 
thickened.     The  fibula  is  a  more  slender  bone  than  the  tibia,  and 
is  longer.     Its  proximal  end  is  thickened  and  subquadrate  in  shape; 
the  lower  end  is  thin  and  con- 
siderably expanded. 

Hind  foot. — As  already 
stated,  the  foot  bones  of  speci- 
men No.  8 1 1  were  more  or  less 
weathered.  From  the  wash 
numerous  toe  bones  and  the 
ends  of  the  epipodials  with 
attached  carpals  had  been 
gathered  up  by  Mr.  Baldwin, 
and  some  of  them  still  retain 
enough  of  their  original  ma- 
trix to  show  their  relation- 
ships, but  how  many  of  them 
are  irretrievably  lost  cannot 
be  determined  at  present. 
Fortunately,  however,  in 
specimen  No.  809  the  tibia 
and  fibula  of  both  sides  were 
pieserved  in  position  with  the 
tarsal  bones  attached;  fortu- 
nately, since  one  would 
hardly  have  identified  the 
tarsal  bones  correctly  had 
they  been  found  isolated,  so 
very  different  are  they  from 
the  corresponding  bones  of  the 
Pariotichidae  orPelycosauria. 
The  tibiale  is  nearly  cuboidal 
in  shape,  with  a  slight  notch 
only  between  the  articular 
facets  for  the  tibia  and  fibula. 
Its  outer  facet  is  thickened  for 
union  with  the  fibulare,  but  I 


IK 


FIG.  16. — Limnoscelis  paludis.  Right 
hind  leg,  dorsal  side,  specimen  No.  809,  two- 
fifths  natural  size.  /+/',  fused  intermedium 
and  tibiale. 


44 


AMERICAN  PERMIAN  VERTEBRATES 


see  no  perforating  foramen  between  the  two  bones.  The  distal 
and  inner  facets  are  also  very  broad,  subquadrate  in  outline,  with 
rounded  angle.  The  fibulare  is  a  larger  bone,  but  much  thinner 
than  the  tibiale;  its  tibial  side  is  the  thickest.  I  identify  these 
two  bones  as  the  usual  fused  tibiale  and  intermedium,  and  the 
fibulare,  but  it  is  not  impossible  that  the  tibiale  has  been  entirely 
lost,  after  fusion,  and  that  what  really  remains  are  the  intermedium 

and  fibulare.  I  have  so  far  found  no 
evidence  satisfactory  to  me  that  the 
tibiale  and  intermedium  are  ever  pres- 
ent in  adult  reptiles  as  distinct  bones. 
I  am  aware  that  Broom  has  provision- 
ally recognized  a  separate  intermedium 
in  Howesia,  and  that  other  instances 
have  been  cited ,  but  I  think  they  are  all 
open  to  doubt.  The  separation  of  the 
intermedium  of  the  hand  is  a  very  per- 
sistent character  in  the  Amniota,  man 
himself  even  having  the  same  bones  that 
are  found  in  the  temnospondyls  in  the 
proximal  row  of  the  carpus.  In  the  tar- 
sus, however,  there  was  an  early  speciali- 
zation as  far  back  as  early  Carbonifer- 
ous times,  and  I  do  not  think  there  was 
ever  a  reversion  to  the  amphibian  type. 
Of  the  left  foot  of  specimen  908  only 
these  two  tarsal  bones  and  a  number  of 
separated  toe  bones  have  been  recovered. 
Of  the  right  foot,  however,  all  the  bones 
of  the  toes  were  preserved  in  their  natural  relations  in  the  matrix, 
or  with  but  slight  distortions,  the  metatarsals  all  lying  in  one  plane, 
apparently  quite  in  the  positions  they  occupied  in  life.  The  block 
containing  them  had  the  phalanges  of  the  first  toe,  the  first  one  of 
the  second  toe,  the  first  two  of  the  third  toe,  and  all  four  of  the  fifth 
toe  in  close  articulation,  those  of  the  first  and  fifth  toes  strongly 
flexed.  With  this  block,  but  separated,  were  the  phalanges  of  the 
middle  toes,  the  two  each  of  the  second  and  third  and  all  five  of 


FIG.  17. — Eosauravus  copei 
Williston.  The  oldest  known 
reptilian  tarsus  and  foot.  Mid- 
dle Pennsylvanian. 


R&PTILIA:  LIMNOSCELIS  45 

the  fourth  toe  severally  connected  by  matrix,  but  not  positively 
attachable  to  the  basal  bones  of  their  respective  digits,  because  of 
the  effacement  of  the  matrical  surfaces  in  collecting.  That  they 
belong  with  these  toes  is,  however,  beyond  doubt,  both  because  of 
their  perfect  anatomical  association  and  the  peculiarities  of  the 
matrix.  The  formula  as  is  thus  seen  is,  like  that  of  the  front  feet, 
the  primitive  one  for  reptiles,  2,  3,  4,  5,  4.  The  phalanges,  as  of 
the  front  feet,  are  all  remarkably  short  and  broad,  and  I  may  also 
add,  relatively  thin.  The  ungual  phalanges,  as  have  been  described 
for  Diadecfes,  which  they  resemble,  are  short,  broad  and  hoof -like 
rather  than  claw-like,  with  a  thin  rounded  extremity,  the  bones 
possibly  incased  in  a  horny  nail  in  life.  I  can  hardly  conceive  of  a 
foot  of  this  character  being  used  for  burrowing,  notwithstanding 
Case's  comparison  of  the  similar  feet  of  Diadectes  with  those  of  the 
gopher.  The  right  front  foot,  as  preserved  in  the  matrix,  had  the 
tibia  and  fibula,  with  their  attached  proximal  carpals,  pressed  down- 
ward somewhat  below  the  proximal  ends  of  the  metatarsals,  but 
not  a  vestige  is  preserved  in  the  matrix  of  centrale  or  tarsalia,  nor 
is  there  any  tarsal  bone  preserved  with  either  specimen,  save  the 
four  sets  of  proximal  ones.  It  is  not  at  all  impossible,  however, 
that  vestigial,  nodular  tarsalia  may  have  been  ossified,  but  it  is  not 
very  probable  that  they  were.  Chondrification  was  evidently  here 
a  specialization,  and  in  accordance  with  the  almost  universal  rule 
among  terrestrial  vertebrates  we  should  expect  that  the  process 
would  develop  more  rapidly  in  the  hind  than  in  the  front  feet. 

As  bearing  upon  the  probable  aquatic  adaptation  of  the  carpus 
and  tarsus  of  Limnoscelis  and  their  chondrification,  it  will  be  of 
interest  to  compare  the  several  stages  of  evolution  in  their  pro- 
gressive adaptation  to  aquatic  life  in  the  American  genera  of 
mosasaurs,  figures  of  which  will  be  found  in  my  work  upon  the  mosa- 
saurs  in  the  fourth  volume  of  the  University  of  Kansas  Geological 
Survey.  In  Clidastes  (Plate  XXXIII)  it  will  be  observed  that  the 
proximal  row  of  carpal  bones  is  fully  ossified,  all  four  of  them  large, 
the  radiale  largest  of  all.  The  centralia  have  disappeared,  or  what 
is  less  probable  have  united  with  adjacent  bones.  Of  the  carpalia 
the  first  and  fifth  have  disappeared,  leaving  the  second,  third,  and 
fourth  of  nearly  equal  size.  In  the  restorations  the  fifth  and  first 


46  AMERICAN  PERMIAN  VERTEBRATES 

digits  are  placed  in  immediate  contact  with  the  bones  of  the  first 
row;  probably  in  life  they  were  separated  by  a  cartilaginous 
interval.  In  Platecarpus  (Plate  XLIV),  the  radiale  and  pisiform 
have  disappeared,  the  intermedium  and  ulnare  alone  remaining 
with  the  third  and  fourth  carpalia,  the  second  gone.  In  Tylosaurus 
(Plate  XL VIII)  the  ulnare  alone  remains  of  the  carpus,  and  that 
very  small  and  nodular,  though  in  other  specimens  a  very  small, 
nodular  intermedium  is  sometimes  found.  In  Clidastes  hyper- 
phalangy  is  just  beginning,  no  finger  having  more  than  two  extra 
phalanges;  in  Platecarpus  hyperphalangy  had  progressed  until  four  or 
more  may  have  been  acquired  in  some  of  the  digits,  while  in  Tylo- 
saurus as  many  as  twelve  phalanges  are  known  in  the  longest  fingers. 
In  the  tarsus  of  Clidastes  (Plate  XXXVI)  the  co-ossified  tibiale 
and  intermedium  have  their  usual  articulations,  with  only  one  of 
the  other  tarsal  elements  remaining,  probably  the  fourth  tarsale. 
In  Platecarpus  (op.  cit.,  p.  166)  we  have  the  same  bones,  but  all  of 
them  reduced.  In  Tylosaurus  (Plate  L)  the  tarsus  is  not  well 
known,  but,  evidently  as  in  the  carpus,  there  is  only  one  mesopo- 
dial  bone,  the  fibulare,  and  that  is  reduced;  and  hyperphalangy 
here  too  is  carried  to  its  greatest  extent  among  mosasaurs. 

Briefly,  it  is  seen  from  these  illustrations  that  specialization  has 
progressed  in  the  mosasaur  limbs  in  nearly  equal  pace  in  the  front 
and  the  hind  ones,  though,  if  Dollo  is  right,  in  Mosasaurus  (and 
Clidastes  ?)  the  loss  of  the  fifth  toe  behind  indicates  the  usual  greater 
specialization  of  the  hind  feet  over  the  front  ones,  as  in  terrestrial 
animals,  though  we  know  that  this  is  not  always  the  case  among 
aquatic  animals.  Again,  they  show  very  conspicuously  that,  as 
in  the  Thalattosuchia,  specialization  begins  on  the  radial  and  tibial 
sides,  and  progressively  extends  to  the  ulnar  and  fibular  sides.  Per- 
haps this  is  the  explanation  of  the  greatly  reduced  size  of  the 
radiale  in  Limnoscelis,  as  well  as  the  reduced  size  of  the  tibiale  and 
fibulare,  which  have  reached  nearly  the  condition  found  in  Plate- 
carpus.  And,  as  I  have  elsewhere  stated,  it  is  evident  that  Clidastes, 
so  far  as  the  limbs  are  concerned  at  least,  is  the  most  generalized 
genus  known  of  the  Mosasauria,  Tylosaurus  the  most  specialized. 

No  indications  whatever  of  ventral  ribs  are  present  in  either 
specimen.  In  their  place,  however,  the  whole  ventral  region  was 


REPTILIA:  LIMNOSCELIS  47 

covered  by  a  sort  of  plastral  sheath  of  imperfectly  ossified  or  calci- 
fied material.  Patches  of  this  sheath  were  found  scattered  about 
in  the  matrix  below  the  posterior  vertebrae  and  adjacent  regions, 
some  of  them  two  inches  or  more  in  diameter.  I  have  not  yet  had 
an  opportunity  to  examine  the  substance  microscopically  but  to 
the  unaided  eye  it  appears  to  be  loose  bone  tissue.  It  is  quite 
certain  that  the  animal  did  not  have  distinct  ventral  ribs,  or  osseous 
dorsal  scales. 

Habits  and  relationships  of  Limnoscelis. — It  is  almost  superfluous 
for  me  to  point  out,  so  evident  will  it  be  to  everyone,  that  Limno- 
scelis must  have  been  a  subaquatic  or  marsh-dwelling  reptile. 
Of  the  poorly  ossified  or  cartilaginous  carpus  and  tarsus  the  evidence 
is  almost  positive,  and  there  can  be  but  one  explanation,  subaquatic 
habits.  The  limbs  as  a  whole  indeed  are  strongly  suggestive  of  the 
turtles.  The  relationships  of  the  genus  are  unquestionably  closest 
with  Diadectes  of  any  forms  that  we  know,  from  which  it  differs 
chiefly  in  the  elongated  skull,  the  conical,  prehensile  teeth,  the 
absence  of  the  ear  cavity  posteriorly,  the  small  size  of  the  parietal 
foramen,  the  smoothness  of  the  skull  surface,  the  non-expanded 
ribs,  their  apparently  single-headedness  throughout,  the  absence 
of  hyposphenes,  and  the  feebly  ossified  carpus  and  tarsus.  It 
agrees  well  with  Diadectes  in  the  general  structure  of  the  limbs, 
the  arrangement  of  the  skull  bones,  especially  the  union  of  the  pre- 
frontal  and  postfrontal  over  the  orbit,  the  general  structure  of  the 
vertebrae,  with  cylindric  or  prismatic  spines,  etc.  It  agrees  with 
both  Diadectes  and  Pareiasaurus  in  the  very  characteristic  flattened 
occipital  condyle;  and  I  believe  that  when  we  know  more  of  the 
structure  of  the  skull  of  the  latter  genus  we  shall  also  find  more 
evidences  of  affinity  in  these  groups,  to  such  an  extent  that  the 
three  genera  and  Propappus  also  may  perhaps  be  placed  in  the 
same  suborder  of  reptiles;  possibly  also  Pantylus. 


48  AMERICAN  PERMIAN  VERTEBRATES 

Family  Seymouriidae 

Williston,  Journal  of  Geology,  XIX,  237,  May,  1911. 

Skull  triangular,  depressed,  tuberculate.  A  deep  and  narrow 
otic  notch  in  the  temporal  region.  Teeth  slender,  conical,  not 
elongated  in  front.  No  cleithrum.  Arches  of  presacral  vertebrae 
greatly  expanded  and  with  vestigial  spines;  ribs  double-headed 
throughout;  a  single  sacral  vertebra;  tail  short;  no  ventral  ribs. 
Legs  short  and  stout;  carpus  and  tarsus  fully  ossified;  ungual 
phalanges  not  dilated;  tibiale  and  fibulare  small.  Digital  fossa 
extending  to  midway  of  femur,  the  adductor  crest  prominent. 
Occipital  condyle  not  flattened.  An  intertemporal  bone  in  skull. 

SEYMOURIA 

Broili,  Paleontographica,  LI,  81,  1904;  Desmospondylus  Williston,  Bull.  Geol. 
Soc.  Amer.,  XXI,  280,  1910;  Conodectes  (?)  Cope,  Amer.  Nat.,  XXX, 
398,  1896;  Proc.  Amer.  Phil.  Soc.,  XXXV,  129,  1896. 

Seymouria  baylorensis  Broili,  Paleontographica,  loc.  cit.,  PI.  XIII, 
ff.  1-3;  Williston  Jour,  of  Geol.,  XIX,  232,  May,  1911.  Pis. 
XXVI-XXIX. 

Desmospondylus  anomalus  Williston,  Bull.  Geol.  Soc.  Amer.,  XXI,   280, 
PL  XVI. 

There  are  few  Permian  vertebrates  of  more  interest  than  that 
to  which  the  name  Seymouria  baylorensis  has  been  given.  The 
genus  and  species  were  originally  described  by  Dr.  Broili  from  two 
imperfect  skulls,  a  clavicular  girdle  and  a  few  anterior  vertebrae, 
discovered  on  West  Coffee  Creek,  in  Baylor  County,  Texas,  not 
far  from  the  town  of  Seymour.  The  characters,  as  given  by  Dr. 
Broili,  were  most  remarkable,  almost  incredible  for  a  reptile, 
including  a  deep  otic  notch,  previously  known  only  among  amphib- 
ians, and  the  presence  of  all  the  dermal  temporal  elements  of  the 
skull  known  among  the  Stegocephala,  that  is  the  "epiotic,"  dermoc- 
cipital,  supra  temporal,  intertemporal,  squamosal,  and  quadratoju- 
gal.  And  there  was  nothing  whatever  in  the  specimen  as  described  by 
Broili  to  distinguish  the  creature  from  an  amphibian,  save  the  single 
occipital  condyle  and  the  structure  of  the  palate.  These  two  type 


REPTILIA:  SEYMOURIA  49 

specimens  preserved  in  the  museum  at  Munich  have  remained 
until  recently  the  only  known  ones  of  the  genus.  Two  years  ago 
I  found  on  East  Coffee  Creek,  not  far  from  the  locality  whence 
the  types  came,  several  vertebrae  and  some  fragmentary  limb 
bones,  which  I  referred  provisionally  to  some  unknown  form 
allied  to  Labidosaums,  but  could  in  nowise  associate  with  Sey- 
mouria.  Later  a  series  of  vertebrae  and  numerous  limb  bones 
were  found  on  West  Coffee  Creek,  in  the  immediate  vicinity  of 
the  locality  whence  came  the  original  types,  imbedded  in  clay 
and  intimately  associated  with  an  incomplete  skeleton  of  Trimer- 
orhachis.  Among  this  material  were  parts  of  two  skeletons  of 
almost  identical  size,  and  very  much  smaller  than  the  type  specimen. 
Because  of  their  immaturity,  for  they  are  doubtless  juvenile 
specimens  of  S.  baylorensis ,  they  show  certain  embryonic  characters, 
such  as  the  separation  of  the  arches  and  the  unusually  large  size 
of  the  intercentra,  not  seen  in  the  adult  specimens.  With  no  parts 
in  common  with  the  type  specimens,  as  described  by  Broili,  I 
described  these  specimens  as  pertaining  to  a  new  genus  and  species, 
Desmospondylus  anomalus  (Plate  XXIX),  though  suspecting  that 
they  might  belong  to  some  previously  described  genus  known 
only  from  fragmentary  remains.  More  recently  a  few  bones  of 
this  species  have  been  detected  among  the  skeletons  of  Cacops, 
Varanosaurus,  and  Casea  of  the  remarkable  Cacops  bone-bed  near 
Indian  Creek,  two  or  three  miles  south  of  West  Coffee  Creek.  And 
yet  other  imperfect  specimens  belonging  to  the  same  genus  and 
species  have  been  recognized  among  the  material  obtained  in  earlier 
years,  now  forming  a  part  of  the  Chicago  University  collections. 

In  May,  1910,  however,  Mr.  Miller  was  so  fortunate  as  to 
discover  on  the  Wagner  ranch,  about  a  mile  west  of  the  Craddock 
ranch,  and  about  the  same  distance  west  of  the  spot  where  the  type 
specimens  of  Trematops  and  Trispondylus  were  discovered,  a 
remarkable  specimen  of  this  species  which  is  almost  without  equal 
among  Permian  specimens  from  Texas  for  perfection  of  preserva- 
tion. The  specimen  was  contained  in  a  large,  dark-red,  hard-clay 
nodule  that  had  been  wholly  washed  from  its  bed,  and  broken  into 
four  pieces  scattered  on  the  hillside.  The  only  visible  part  of  the 
specimen  which  led  to  its  detection  was  a  small  part  of  the  cranial 


50  AMERICAN  PERMIAN  VERTEBRATES 

table  of  the  skull,  where  a  chip  had  broken  away  from  the  nodule. 
The  tail  in  part  was  in  a  protuberance  of  the  nodule  that  had  been 
broken  off,  and  was  not  recovered;  I  doubt  not  that  a  diligent 
search  in  the  vicinity  later  will  be  rewarded  by  even  this  part  of 
the  skeleton.  Hidden  in  this  nodule,  which  showed  but  little 
erosion  from  the  rain  and  frost,  the  skilful  preparation  of  Mr. 
Miller  has  revealed  a  very  nearly  complete  skeleton  in  closest 
articulation  from  the  skull  to  the  sixth  caudal  vertebra.  The 
animal  was  doubtless  fossilized  in  a  prone  condition,  since  the 
spinal  column  has  an  undulating  curve  as  pressed  downward  from 
the  apparently  upward  convex  curve  it  had  in  the  recent  skeleton; 
the  tail  was  curved  downward  to  the  end  of  the  ischia,  like  that  of 
a  dog,  the  horizontal  position  beginning  with  the  sixth  caudal 
vertebra;  and  it  is  this  part  which  is  lost.  The  pectoral  girdle  is 
nearly  in  position,  the  right  scapula  and  clavicle  pressed  slightly 
forward,  the  head  turned  slightly  in  the  same  direction.  The 
right  arm,  fully  articulated,  lies  close  to  the  side  of  the  body, 
directed  backward,  the  hand  bones  more  or  less  intermingled  with 
the  bones  of  the  right  foot.  The  left  front  leg  was  flexed  at  the 
elbow  and  turned  forward;  its  metacarpals  alone  are  preserved. 
The  pelvis  also  lies  quite  in  position  below  the  last  lumbar,  the 
single  sacral  and  the  first  four  caudal  vertebrae,  the  parts  all  in 
close  articulation,  save  the  right  ilium,  which  is  very  slightly 
separated  at  the  ischiadic  suture.  Both  femora  are  in  close  articu- 
lation in  the  acetabula,  directed  forward,  upward,  and  a  little 
inward,  and  quite  alike  on  the  two  sides.  And  both  the  forelegs 
are  closely  articulated  with  their  respective  femora,  as  are  the 
individual  bones  with  each  other  on  each  side.  Both  feet  evidently 
lay  close  by  the  sides  of  the  body  originally,  but  with  the  col- 
lapse of  the  abdomen  they  have  been  dragged  somewhat  away 
from  the  ends  of  the  leg  bones. 

No  attempt  has  been  made-  to  free  any  of  the  bones,  nor  could 
they  be  separated  without  danger,  since  they  are  rather  soft  in 
texture,  with  a  thin,  white  outer  layer  that  easily  breaks  away, 
and  many  of  the  bones,  especially  those  of  the  skull,  have  this 
layer  divided  by  many  delicate  cracks,  as  though  the  skeleton  had 
been  more  or  less  exposed  to  the  atmosphere  before  fossilization 


REPTILIA:  SEYMOURIA 


51 


finally  occurred.  One  thing  is  evident,  the  skeleton  had  been 
subjected  to  but  very  slight  or  no  disturbance  from  wind,  waves, 
currents,  or  predatory  animals  after  death.  Nor  do  the  parts  of 
the  skeleton  show  distortion  or  compression,  as  is  so  often  the  case 
with  bones  in  this  and  other  formations. 

Skull. — The  skull  is  very  perfectly  preserved,  the  short  exposure 
of  the  cranial  table  had  injured  it  but  slightly,  and  in  no  wise 
affected  its  shape;  unfortunately,  however,  it  prevents  the  certain 
corroboration  of  the  sutures 
observed  by  Broili,  a  matter 
of  less  regret  since  the  well- 
preserved  skulls  studied  by 
him,  at  least  in  this  region, 
apparently  leave  little  or  no 
doubt  as  to  the  structure. 
The  teeth  also,  because  of 
their  extreme  delicacy,  could 
not  be  worked  out  entire 
from  the  hard  matrix.  This, 
however,  is  not  to  be  greatly 
regretted,  since  between  the 
two  sides  one  is  able  to  de- 
termine the  dentition  quite 
satisfactorily,  in  the  upper 
jaws  at  least.  In  the  outline 
figure  I  have  inserted  those 
sutures  copied  from  Broili 's 
drawings  in  dotted  lines,  while 
those  satisfactorily  determined  in  this  specimen  are  shown  in  con- 
tinuous lines;  others  about  which  I  am  uncertain  I  have  figured 
in  lines  of  small  crosses. 

The  skull  is  elongate,  triangular  in  shape,  nearly  flat  on  the 
upper  surface  between  the  temporal  regions  and  as  far  forward 
as  the  interior  part  of  the  orbits,  the  surface  over  each  orbit  some- 
what convex.  Thenceforward  to  the  tip  of  the  muzzle,  the  profile 
is  somewhat  convex  from  side  to  side,  with  a  steep  declivity  on  each 
side  in  front  of  the  orbit.  The  nares  are  rather  large  and  oval,  or 


FIG.  18. — Seymour -ia  baylorenis.  Skull, 
from  above,  one-half  natural  size,  n,  nasal; 
/,  lachrymal;  £/",pref rental;  />o/,postf rental; 
fr,  frontal;  it,  intertemporal;  st,  supratem- 
poral;  do,  dermoccipital;  t,  tabulare. 


52  AMERICAN  PERMIAN  VERTEBRATES 

sub  triangular  in  shape.  The  orbits,  situated  a  little  back  of  the 
middle  of  the  skull,  are  not  large,  trapezoidal  in  shape,  the  roof 
somewhat  convex,  the  anterior  inferior  angle  acute.  The  plane  of 
their  opening  looks  outward  and  a  little  upward.  The  otic  notch 
has  for  its  roof  the  thickened  outer  border  of  the  cranial  table, 
its  immediate  upper  border  undulating  in  outline,  the  anterior 
ends  somewhat  constricted,  both  on  the  upper  and  lower  margin, 
by  a  slight  protuberance,  leaving  the  extremity  in  the  shape  of 
about  three-fifths  of  a  circle,  probably  for  the  auditory  meatus 
and  stapes.  From  the  protuberance  on  the  lower  margin,  the  bor- 
der of  the  notch  curves  downward  and  backward  convexly  to  the 


FIG.  19. — Seymour  la  baylorensis .  Skull  and  pectoral  girdle,  from  the  side,  one- 
half  natural  size,  pm,  premaxilla;  m,  maxilla;  /,  lachrymal;  n,  nasal;  pf,  pref rental; 
j,  jugal;  po,  postorbital;  sg,  squamosal;  qj,  quadra  to  jugal;  d,  clavicle;  ic,  inter- 
clavicle;  sc,  scapula;  c,  coracoid. 

quadrate  articular  end.  The  positions  of  the  sutures,  as  shown  in 
the  figure,  will  need  no  explanation.  On  the  upper  side,  those  made 
out  with  tolerable  certainty  are  indicated  by  lines  of  small  crosses, 
those  copied  from  Broili  by  dots.  I  am  least  sure  of  the  intertem- 
poral,  a  remarkable  stegocephalian  bone  unknown  in  other  rep- 
tiles; I  think,  however,  there  are  indications  of  it  in  this  specimen. 
The  sutures,  as  shown,  agree  clearly  with  those  given  by  Broili. 
The  maxillary  teeth  are  elongate  and  slender,  curved  downward 
and  gently  backward.  I  cannot  be  sure  of  the  number  in  the  pre- 
maxillae,  but  there  were  at  least  three,  and  the  ones  remaining  are 
shorter  than  those  following  them  in  the  maxillae.  I  count  eighteen 


REPTILIA  :  SEYMOURIA  53 

teeth  in  each  maxilla,  though  there  may  be  one  or  two  more  or 
less,  the  longest  of  them  in  the  middle  or  front  part;  they  are  placed 
close  together  and  are  evidently  labyrinthine  in  structure.  They 
extend  back  nearly  as  far  as  the  posterior  inferior  angle  of  the  orbit. 
The  mandibular  teeth  cannot  be  made  out  in  the  closed  condition 
of  the  jaws.  The  mandibles  are  rather  slender,  meeting  in  a  short 
symphysis,  curving  broadly  outward  behind,  and  are  broadest 
below  the  posterior  part  of  the  orbit.  The  articular  bone  is  pro- 
duced very  slightly. 

The  occipital  region  of  the  skull  is  obscured  by  the  articulated 
vertebrae  above  and  the  clavicular  arch  below;  I  can  say  nothing 
concerning  it.  And  of  the  palatal  region  only  the  anterior  part, 
in  front  of  the  clavicles,  is  visible.  Broili  describes  these  regions 
as  follows: 

The  basioccipital,  showing  only  a  comparatively  small  surface,  has  a  well 
formed,  lightly  convex  occipital  condyle.  The  basisphenoid  has  its  lateral 
processes  considerably  developed  as  keel-like  elevations;  anteriorly  it  is  drawn 
out  into  a  pointed,  dagger-like  parasphenoid,  projecting  into  the  space  between 
the  pterygoids.  The  anterior  wing  of  the  pterygoid  is,  at  the  beginning,  gently 
emarginate,  forming  the  interval  for  the  parasphenoid,  but  it  soon  unites  with 
the  corresponding  wing  of  the  opposite  side.  The  extent  of  the  united  ptery- 
goids in  front  is  considerable,  though  how  great  cannot  be  said  because  of  the 
imperfect  preservation  of  the  specimen.  The  posterior  process  of  the  ptery- 
goids extends  dorsalward  in  the  region  of  the  quadrate,  forming  on  one  side 
the  border  of  the  inferior  temporal  vacuity,  on  the  other  taking  part  in  the 
formation  of  the  otic  notch.  On  the  margins  of  the  anterior  processes  of  the 
pterygoid  which  form  the  interpterygoid  vacuity,  as  also  on  the  elevation,  there 
are  traces  of  small  teeth;  but  the  preservation  of  the  specimen  does  not  permit 
the  determination  of  the  number. 

In  the  present  specimen  only  the  very  broad  pterygopalatine 
plates  in  front  of  the  temporal  vacuity  have  been  exposed.  They 
slope  upward  on  each  side  at  an  angle  of  nearly  forty-five  degrees. 
The  separation  of  the  sutures,  alike  on  the  two  sides,  seems  to 
differentiate  the  pterygoids,  palatines,  and  vomers.  The  palatines 
are  narrow,  reaching  back  only  to  the  beginning  of  the  declivity 
representing  the  transverse  bone;  the  union  between  the  vomers 
and  pterygoids  is  broad.  I  can  distinguish  no  teeth  of  any  kind 
on  any  of  the  bones;  doubtless  they  were  present,  though  in  all 
probability  very  small. 


54  AMERICAN  PERMIAN  VERTEBRATES 

The  presacral  vertebrae,  as  stated,  are  all  in  close  articulation; 
the  number  is  positively  fixed  at  twenty-three.  It  is  worthy  of 
note  how  common  this  number  of  presacral  vertebrae  seems  to  be 
among  the  early  land  vertebrates.  It  is  the  number  I  concluded 
was  present  in  the  temnospondyl  Trematops,  apparently  the  number 
in  Sauravus,  Hylonomus,  Eosauravus,  and  in  Captorhinus.  In 
Limnoscelis  there  are,  apparently,  twenty-five,  though  this  is  not 
certain.  In  Cacops,  a  temnospondyl,  there  are  twenty-one,  with 
perhaps  twenty-four  in  Eryops.  Among  the  higher  reptiles,  Cased 
has  twenty-four,  Varanosaurus  and  Dimetrodon,  twenty-seven. 

Nothing  is  more  conspicuous  in  the  skeleton  of  Seymouria  than 
the  great  development  of  the  neural  arches  of  the  presacral  verte- 
brae, especially  posteriorly;  and  the  abrupt  change  from  the  broad 
overroofing  form  of  the  presacrals  to  the  narrow,  more  slender  form 
of  the  caudals.  Not  much  can  be  seen  of  the  atlas  and  axis,  but, 
from  the  third  vertebra,  the  arches  increase  rapidly  in  transverse 
expansion  to  the  eighth  or  ninth;  that  is,  throughout  those  bearing 
the  distally  dilated  ribs.  With  the  ninth,  the  arches  have  acquired 
nearly  or  quite  their  full  width,  remaining  uniform  to  the  sacrum. 
On  the  first  three  or  four  vertebrae  there  are  distinct,  though  small, 
spines,  perhaps  six  or  eight  millimeters  in  height;  from  the  fourth  to 
the  sacrum  the  spines  are  mere  tubercles.  The  structure  of  the 
posterior  vertebrae  will  be  made  sufficiently  plain  from  the  figures 
given  in  Plate  XIII,  Figs.  5-8,  from  a  vertebra  found  in  the 
Craddock  bone-bed,  and  from  an  isolated  specimen  found  on  Coffee 
Creek.  The  zygapophyses,  it  is  seen,  are  very  broad  and  flat. 
The  diapophyses  are  small  protuberances  rising  high  up  from  tlie 
sides  of  the  anterior  zygapophyses;  from  the  eighth  vertebra  to 
the  sacrum  they  do  not  project  beyond  the  border  of  the  zygapo- 
physes; in  front,  however,  they  extend  beyond  them  conspicuously, 
their  expanse  as  great  as  on  the  posterior  vertebrae.  The  centra 
are  subcylindrical,  with  the  lower  border  shorter,  in  some  very 
much  shorter,  than  the  length  of  the  neural  canal,  allowing  space 
for  the  large  intercentra.  The  intercentra  are  not  as  large  propor- 
tionally in  the  adult  specimens  as  in  the  young,  as  figured  and  de- 
scribed by  me  in  Desmospondylus  (Plate  XXIX).  Nevertheless 
they  are  unusually  large  for  a  reptile  in  the  adult  even,  so  large 


REPTILIA  :  SEYMOURIA  55 

that  the  head  of  the  rib  articulated  with  them  on  the  sides.  The 
sutures  separating  the  arch  from  the  centrum  are  not  visible  in  the 
adult  specimens. 

The  single  sacral  vertebra  resembles  that  immediately  pre- 
ceding, except  that  it  is  larger  and  stouter,  but  no  wider,  and  its 
diapophyses  are  very  heavy  and  stout,  though  not  extending  farther 
outward.  The  arch  was  somewhat  injured  in  preparation,  and  I 
can  say  little  regarding  its  spine,  though  enough  is  left  to  indicate 
that  it  was  longer  than  on  the  vertebrae  immediately  in  front.  It 
probably  was  nearly  as  long  as  the  spine  of  the  first  caudal  vertebra. 
Five  caudal  vertebrae  are  preserved  in  position,  together  with  a 
part  of  the  sixth.  Their  arches,  it  is  seen,  are  very  much  narrower 
than  those  of  the  presacrals,  but  their  centra,  at  least  in  front, 
are  not  much  smaller.  The  spines  are  elongate,  rather  slender, 
and  pointed,  and  are  directed  obliquely  backward.  The  dia- 
pophyses do  not  extend  outward  as  widely  as  those  of  the  sacrum. 
The  chevrons,  preserved  on  the  fourth  and  fifth  vertebrae,  are 
unusually  stout. 

Many  of  the  ribs  cannot  be  exposed  in  their  entirety.  The 
transverse  processes  of  the  atlas  and  axis  do  not  bear  ribs,  but, 
lying  below  them  and  above  the  clavicle  on  the  left  side  are  two 
slender  ribs,  partly  exposed,  that  evidently  belong  here.  From  the 
third  vertebra  to  the  ninth  the  articulated  ribs  are  expanded  dis- 
tally  and  quite  surely  overlap  each  other  at  their  ends,  since  the 
antero-posterior  extent  of  the  middle  ones  is  greater  than  the  length 
of  the  centra  bearing  them.  The  terminal  expansion  is  greatest 
on  the  sixth,  where  the  width  is  twenty  millimeters.  The  expan- 
sion of  the  seventh  is  materially  less  than  that  of  the  sixth, 
and  that  of  the  ninth  is  not  more  than  two  or  three  times  greater 
than  the  width  of  its  shaft.  As  far  as  the  eighteenth  or  nineteenth 
at  least — as  far  as  I  am  able  to  follow  them — the  distal  end  is  slightly 
greater  in  breadth  than  the  width  of  its  shaft.  In  length  the  ribs 
do  not  vary  much,  at  least  the  first  eighteen  or  twenty  pairs  do 
not.  Posteriorly  the  ribs  are  clearly  double-headed,  and  I  believe 
that  they  are  so  throughout,  though  I  cannot  be  quite  sure  of  the 
first  three  or  four  pairs. 

The  single  sacral  rib  on  each  side  has  a  heavy  tubercle  for  union 


56  AMERICAN  PERMIAN  VERTEBRATES 

with  the  diapophysis,  below  which  it  is  broadly  dilated  antero- 
posteriorly,  fitting  closely  the  whole,  or  nearly  the  whole,  of  the 
inner  side  of  the  upper,  dilated  part  of  the  ilium,  from  the  extreme 
posterior  angle  forward,  leaving  no  space  whatever  for  the  attach- 
ment of  a  second  rib,  however  small.  Five  caudal  ribs  are  in  place 
on  the  right  side,  loosely  attached  to  the  ends  of  the  diapophyses. 
The  first  of  these,  on  the  first  caudal  vertebra,  is  separated  from 
the  sacral  rib  and  is  slender  like  the  following  ones;  its  distal  end, 
as  preserved,  is  pointed,  and  the  rib  is  shorter  than  the  next  fol- 
lowing one.  I  cannot  be  sure  but  that  the  end  is  the  result  of 
fracture,  the  more  so  as  a  part  of  a  rib  lies  transversely  below  it. 
In  the  figure  I  have  restored  the  rib,  with  lines,  to  the  form  of  the 
following  ones,  but  I  am  inclined  to  believe  that  the  whole  rib  is 
present,  and  that  the  one  below  it  belongs  with  the  opposite  side. 
However,  even  if  short,  it  could  have  had  no  part  in  the  support 
of  the  ilium,  nor  did  it  even  touch  it,  proving  conclusively,  for  the 
first  time,  I  believe,  the  presence  of  but  a  single  sacral  vertebra  in 
a  reptile.  All  of  the  caudal  ribs  preserved  are  slightly  dilated  and 
flattened  at  their  distal  extremity.  They  do  not  decrease  much 
in  length,  from  which  it  would  appear  that  the  tail  in  life  was 
ribbed  for  a  considerable  part  of  its  extent. 

Pectoral  girdle  and  extremity. — The  pectoral  girdle  has  suffered 
little  distortion  or  displacement;  on  the  right  side  it  is  thrust 
forward  a  little,  or,  on  the  opposite  side,  backward.  The  expanded 
parts  of  the  clavicles,  in  close  articulation  with  the  interclavicle, 
lie  under  the  occipital  region,  close  up  to  the  angle  of  the  jaws. 
The  ascending  more  slender  part  of  the  clavicles  is  applied  rather 
closely  to  the  quadrate,  permitting  very  little  lateral  movement 
of  the  skull  on  the  vertebral  column.  The  larger  part  of  the  inter- 
clavicle  is  hidden  above  the  clavicles,  leaving  only  a  diamond- 
shaped  surface  exposed  in  the  middle  behind.  Its  stem  is  stout 
and  rather  broad,  oval  in  cross-section,  tapering  slightly  to  about 
its  middle,  and  then  gently  expanded  to  the  extremity,  which 
reached  as  far  as  the  eighth  or  the  beginning  of  the  ninth  vertebra, 
and  far  back  of  the  coracoid.  The  clavicles  are  much  dilated  on 
the  ventral  side,  with  a  convex  thin  border  in  front  to  near  the 
angle  of  the  jaws,  where  it  turns  sharply  upward,  backward,  and  a 


REPTILIA  :  SEYMOURIA 


57 


little  outward.  This  ascending  part  is  thin  on  the  ascending 
outer  convex  border,  its  anterior  surface  looking  outward  at  an 
angle  of  nearly  forty-five  degrees,  to  near  the  top,  where  the  bone 
is  continued  more  slenderly  quite  to  the  upper  angle  of  the  clavicle, 
touching  or  articulating  with  the  front  border.  For  the  greater 
part  of  its  extent  the  thin  border  projects  out  from  the  scapula, 
and  is  not  applied  to  its  outer  face.  On  neither  side  is  there  any 
indication  of  a  cleithrum,  and  as  no  indications  of  this  bone  were 
found  by  Broili  in  his  specimens,  I  think  it  may  be  said  definitely 
there  was  none.  In  its  absence  the  genus  is  differentiated  from 
both  Diadectes  and  Lim- 
noscelis  and  allied  to 
Labidosaurus.  The  right 
scapula  lies  very  perfect- 
ly in  place  and  is  visible 
in  nearly  its  whole  ex- 
tent from  without,  save 
the  lower  front  angle 
overlain  by  the  clavi- 
cle. On  the  left  side  it 
is  thrust  back  more,  and 
is  partly  hidden  beneath 
the  overlying  humerus. 
The  blade  of  the  scapula 
is  considerably  broader 
above  than  below;  its 
posterior  border  is  rather  deeply  concave,  its  anterior  thin,  and 
the  upper  end  is  truncate,  thicker  posteriorly,  for  cartilage.  The 
suture  separating  the  scapula  from  the  coracoid,  as  in  other  ver- 
tebrates from  Texas  where  it  has  been  observed,  passes  forward 
from  just  above  the  posterior  glenoid  facet,  through  the  middle 
of  the  anterior  facet,  to  the  front  border  rather  high  up.  The 
supraglenoid  fossa  is  rather  broad  and  has  at  its  upper  part  the 
usual  supraglenoid  foramen.  The  glenoid  fossa  is  short  antero- 
posteriorly,  truncated  posteriorly,  with  a  cartilaginous  border,  very 
much  as  in  Varanosaurus,  as  figured  in  Plate  V.  It  is  evident  that 
here  too  the  real,  so-called  coracoid  was  never  ossified,  but  remained 


FIG.  20. — Seymouria  baylorensis.  Pectoral  girdle, 
from  below,  one-half  natural  size,  cl,  clavicle;  ;V, 
interclavicle;  c,  coracoid;  sc,  scapula. 


58  AMERICAN  PERMIAN  VERTEBRATES 

as  a  cartilaginous  extension  throughout  life.  The  scapula  mentioned 
by  me  in  my  paper  on  Cacops  (Bull.  Geol.  Soc.  Amer.,  XXI,  268, 
near  bottom)  as  having  the  posterior  part  unossified  I  find  really 
belongs  with  Seymouria,  though  resembling  in  other  ways  that  of 
Cacops  so  much  as  to  be  practically  indistinguishable.  The  supra- 
coracoid  foramen  pierces  the  bone  in  its  usual  place,  below  the 
scapula-coracoid  suture  a  little  in  front  of  the  preglenoid  facet, 
at  the  bottom  of  a  rather  large  fossa.  Between  this  foramen  and 
the  posterior  cartilaginous  border  the  smooth  surface  shows  not 
the  slightest  indication  of  a  suture.  Inasmuch  as  the  sutures 
elsewhere  are  all  more  or  less  patent,  it  is  quite  impossible  that  the 
posterior  coracoid  should  be  ossified  here,  and  even  if  ossified  it 
must  be  merely  vestigial  and  wholly  below  the  scapula.  There 
cannot  be  the  least  doubt  but  that  the  posterior  bone,  the  so-called 
coracoid,  is  unossified  in  Seymouria,  as  in  Varanosaurus,  and  that 
precisely  this  same  condition  with  the  sutures  in  the  same  place 
I  have  observed  in  a  scapula-coracoid  which  I  refer  provisionally 
to  Aspidosaurus  peltatus,  described  elsewhere  in  this  work.  The 
coracoid  of  all  these  forms  consists  exclusively  of  the  anterior 
element,  the  so-called  procoracoid.  That  this  bone  has  entirely 
disappeared  in  all  later  reptiles,  giving  place  in  its  entirety  to 
another  bone,  here  unossified,  with  like  attachments,  and  with  its 
perforating  supracoracoid  foramen  in  the  same  position,  I  cannot 
believe.  On  the  other  hand,  Broom  has  brought  arguments  to 
show  that  the  coracoid  process  of  the  mammals  really  represents 
the  posterior  element,  and  that  it  is  the  anterior  one,  the  procora- 
coid, which  has  disappeared  in  the  mammals.  Whether  his  views, 
the  ones  generally  accepted  for  all  the  later  vertebrates,  will 
eventually  be  proven  beyond  doubt  for  the  mammalia,  I  am  not 
competent  to  predict.  That  there  have  been  two  divergent 
methods  of  development  of  the  coracoid  in  the  amniota  is  not,  of 
course,  impossible,  nor  perhaps  at  all  improbable.  The  absence 
of  a  perforating  coracoid  foramen  in  the  mammalia,  and  its  almost 
universal  presence  in  the  reptilia  (absent  only  in  the  Pterosauria, 
and  I  am  not  sure  but  even  in  that  order  the  opening  back  of  the 
glenoid  fossa  as  I  have  described  it  really  represents  this  foramen) 
may  indicate  a  different  mode  of  ossification.  In  any  event  it 


REPTILIA  :  SEYMOURIA  59 

seems  to  me  utterly  improbable  that  the  coracoid  as  ossified  in 
the  Seymouria  and  V aranosaurus  is  not  identical  with  the  bone 
supposed  to  be  (without  proof)  the  fused  coracoid  and  procora- 
coid  of  the  Lacertilia,  Dinosauria,  etc.  I  at  first  adopted  the  terms 
of  Howes  and  Lydekker,  calling  the  anterior  bone  in  these  animals 
the  real  coracoid  and  the  posterior  one,  the  metacoracoid,  but,  in 
deference  to  the  arguments  brought  forward  by  Broom,  I  will  beg 
the  question,  until  its  final  decision,  by  simply  calling  the  two  bones 
the  "anterior*"  and  the  "posterior"  coracoids.  The  only  thing 
that  I  wish  to  insist  upon  is  that  the  coracoid  of  Seymouria  and 
Varanosaurus  is  absolutely  identical  with  the  coracoid  of  the 
Lacertilia,  Dinosauria,  Crocodilia,  etc. 

The  humerus  (Plate  XXIX)  is  a  remarkably  short  and  stout 
bone  with  a  large  ectepicondylar  process,  characteristic  of  this 
genus,  the  Diadectidae,  Limnoscelidae  and  Eryopidae,  but  not 
found  in  the  Pariotichidae,  and  most  of  the  temnospondyles.  The 
median  or  ulnar  process  is  also  large,  and  the  entepicondylar 
foramen  is  of  unusual  size;  the  entocondyle  is  greatly  expanded. 
The  radius,  as  preserved  in  this  specimen,  is  a  more  slender  bone 
than  the  one  figured  by  me  in  Desmospondylus,  possibly  indicative 
of  specific  differences.  Its  shaft  is  only  moderately  stout,  the 
proximal  end  subcylindrical  and  truncated,  and  but  moderately 
expanded  at  the  distal  end,  less  than  is  shown  in  the  figure.  The 
olecranon  is  well  developed.  There  are  several  carpal  bones  lying 
in  association  with  their  respective  arm  bones,  though  but  little 
can  be  said  regarding  their  identities  and  associations;  they  are 
all  small.  The  hand  bones  of  the  right  side  are  more  or  less  inter- 
mingled with  the  bones  of  the  right  foot,  and  some  of  them  cannot 
be  differentiated.  On  the  left  side,  however,  four  metacarpals 
are  yet  lying  in  orderly  relations,  and  it  is  from  the  two  sides  that 
I  have  restored  the  hand  as  shown  in  the  figure.  Among  the  pha- 
langes are  one  or  two  of  small  size,  demonstrating  the  slenderness 
of  the  fingers,  and  their  consequent  differentiation  from  those  of 
Limnoscelis  and  Diadectes.  The  number  of  phalanges,  as  given  in 
the  figure,  both  of  the  front  and  the  hind  feet,  is  assumed,  but 
there  can  be  little  doubt  but  that  the  formula  was  the  primitive 
one,  as  in  Limnoscelis. 


60  AMERICAN  PERMIAN  VERTEBRATES 

Pelvic  girdle  and  extremity. — The  pelvis  has  suffered  little  dis- 
tortion or  displacement,  lying  below  the  first  two  presacral,  the 
sacral,  and  the  first  two  or  three  caudal  vertebrae.  The  sutures 
between  the  different  elements  are  all  rather  widely  separated. 
The  pubes  are  subquadrate  or  trapezoidal  in  outline,  considerably 
broader  at  their  front  border  than  at  the  pubo-ischiadic  suture. 
The  front  border  of  each  is  gently  convex  in  outline,  and  the  two 
are  convex  from  side  to  side  below,  without  the  median  keel  so 
characteristic  of  Limnoscelis.  The  rather  small  obturator  foramen 


FIG.  21. — Seymouria  baylorensis.  Pelvic  girdle  and  femora,  from  below,  one- 
half  natural  size,  pb,  pubis;  is,  ischium;  il,  ilium;  /,  right  femur,  tibial  side,  as  articu- 
lated; Jf,  femur  of  Craddock  bone-bed  specimen,  ventral  side,  a  little  more  than  half 
natural  size. 

is  situated  not  far  from  the  acetabular  ischiadic  angle.  The  ischia 
are  very  nearly  twice  the  length  of  the  pubes,  rather  deeply  con- 
cave on  the  sides  back  of  the  acetabular  angle,  somewhat  expanded 
behind;  the  posterior  border  with  an  undulating  outline,  but  with- 
out a  very  pronounced  median  emargination.  In  the  middle 
there  is  a  pronounced  keel,  thickest  and  broadest  about  midway 
of  the  bones.  The  ilia  are  unusually  narrow  antero-posteriorly 
between  the  upper  and  lower  expansions;  they  are  relatively  high. 
The  front  border  is  nearly  vertical,  gently  convex  anteriorly  above; 
the  upper  border  is  thin,  sloping  downward  and  outward  to  a 
narrow  process  posteriorly.  The  posterior  iliac  notch  is  deep  and 


KEPT  I  LI  A  :  SEYMOURIA  61 

broad,  the  border  sloping  upward  in  a  curve  from  the  ischiadic 
suture ;  the  hind  end  of  the  process  reaches  as  far  back  nearly  as  the 
hind  end  of  the  first  caudal  vertebra.  The  ilia  are  in  perfect 
articulation  with  the  sacral  ribs  which  were  attached  high  up, 
their  upper  margins  even  showing  above  the  iliac  border  in  its 
middle.  The  proximal  end  of  the  rib  of  the  first  presacral  vertebra 
lies  against  the  upper  front  margin  of  the  ilia,  evidently  extending  a 
short  distance  beyond  the  margin  freely  in  life.  The  inner  side 
of  the  pelvis  of  course  cannot  be  seen,  and  the  acetabula  are  par- 
tially filled  by  the  proximal  ends  of  the  femora.  It  is  apparent, 
however,  that  the  pelvic  opening  was  large  and  roomy.  The  femora, 
as  has  been  stated,  lie  in  close  articulation  with  their  respective 
acetabula,  both  directed  upward,  forward,  and  a  little  inward,  the 
knee  on  each  side  precisely  reaching  the  end  of  the  posterior  zyga- 
pophyses  of  the  fourth  presacral  vertebra;  and  their  positions 
are  identical  on  the  two  sides,  the  large  digital  fossa  looking  almost 
outward  and  slightly  ventrad.  The  femur  agrees  closely  with  the 
one  referred  by  me  to  Desmospondylus  n.  sp.  in  the  cited  paper  from 
the  Cacops  bone-bed,  save  that  it  is  slightly  larger.  In  the  accom- 
panying figure  the  femur  is  shown  in  the  position  in  which  it  lies 
on  the  left  side ;  with  it  is  a  figure  of  the  ventral  side  of  the  Cacops 
bone-bed  specimen  a  little  more  enlarged.  Like  the  diadectid, 
limnoscelid,  and  eryopid  femora,  it  is  remarkable  for  the  enormous 
size  of  the  digital  fossa  and  the  high  adductor  crest.  On  the  two 
sides  the  bones  of  the  forelegs  are  in  close  articulation  with  their 
respective  femora,  both  flexed  at  an  angle  of  very  nearly  forty-five 
degrees,  and  directed  a  little  outward.  Evidently  they  had  lain 
closely  by  the  side  of  the  abdomen;  and  the  posterior  ribs  are  yet 
hidden  between  the  forelegs  and  the  vertebra  in  large  part.  The 
tibiae,  so  far  as  they  have  been  exposed,  agree  well  with  the  one 
figured  of  Desmospondylus.  They  are  remarkably  short  and  stout 
bones.  The  upper  ends  of  the  fibulae  are  yet  partly  hidden  below 
the  tibiae,  with  which  they  are  in  perfect  association;  distally  they 
are  remarkable  for  their  great  expansion,  indicative  of  a  broad  foot. 
On  the  left  side  the  proximal  tarsal  bones  are  nearly  in  position 
with  the  ends  of  the  leg  bones,  and  in  close  union  with  each  other. 
They  are  remarkably  small.  The  tibiale  is  subcircular  or  sub- 


62  AMERICAN  PERMIAN  VERTEBRATES 

quadrate  in  shape,  nearly  as  thick  as  broad.  The  fibulare  is 
broader  from  side  to  side  than  longitudinally,  a  little  narrower 
than  is  shown  in  the  figure.  On  the  radial  side  three  tarsal  bones 
and  a  part  of  a  fourth  are  seen  nearly  in  place,  evidently  the  cen- 
trale  and  the  first,  second,  and  third  tarsalia.  The  first  tarsale  is  a 
very  small  bone ;  the  second  is  larger,  larger  somewhat  than  is  shown 
in  the  figure;  and  the  centrale  is  also  very  small.  On  the  outer 
side  a  part  of  a  small  tarsale  is  seen  closely  applied  to  the  fibulare. 
The  fourth  and  fifth  metatarsals  cover  the  other  tarsalia,  indica- 
tions of  which  are  seen  below  them.  It  is  very  evident  that  the 
tarsus  was  small,  the  bones  being  all  closely  articulated  with  each 
other  without  intervening  cartilage.  The  five  metatarsals  lie  in 
natural  positions,  the  proximal  end  of  the  fifth,  only,  thrust  up  a 
little  over  that  of  the  fourth.  The  first  is  a  very  short  bone,  its 
width  proximally  equaling  its  length;  the  third  is  the  broadest  and 
heaviest;  the  fourth  is  the  longest;  while  the  fifth  is  only  a  little 
shorter,  indicating  a  strong  fifth  toe.  In  articulation  with  the  first 
metatarsal  is  its  first  phalange ;  the  short  first  phalange  of  the  fifth 
toe  also  lies  closely  in  relation  with  the  metatarsal,  while  its  second 
phalange  has  been  thrust  in  between  the  fourth  metatarsal  and  its 
first  phalange.  A  little  distance  beyond  the  three  middle  metatar- 
sals are  a  series  of  three  small  phalanges,  evidently  distal  ones  of 
these  toes,  the  intervening  ones  hidden  or  missing;  they  lie  upon 
or  rather  below  the  distal  ends  of  ribs,  which  has  caused  their  dis- 
placement. From  these  phalanges  it  is  quite  certain  that  the  toes 
distally  were  slender,  with  narrow  ungual  phalanges  quite  unlike 
those  of  Limnoscelis  and  Diadectes.  As  I  cannot  place  these  small 
phalanges  in  their  respective  toes,  they  are  not  indicated  in  the 
restoration.  Nor,  of  course,  can  it  be  said  definitely  what  the 
phalangeal  formula  was,  though  there  would  seem  to  be  little 
doubt  that  this  genus  agrees  with  Limnoscelis  in  having  the  primi- 
tive one,  2,  3,  4,  5,  4. 

From  the  material  described,  I  have  made,  after  painstaking 
study,  the  restoration  as  shown  in  the  figure,  about  one-third  natu- 
ral size.  The  conjectural  parts,  shown  by  the  uniformly  ruled  lines, 
are  the  length  of  the  tail,  the  structure  of  the  carpus,  and  the 
arrangement  of  the  phalanges.  The  length  of  the  tail  I  have  esti- 


REPTILIA  :  SEYMOURIA  63 

mated  from  the  accurately  measured  taper  of  the  six  proximal 
vertebrae,  and  upon  the  whole,  I  think  it  is  too  long.  However, 
it  is  possible  that  the  distal  vertebrae  may  have  been  elongated, 
and  the  tail  even  longer  than  is  shown.  At  the  first  opportunity 
search  will  be  made  in  the  locality  where  the  specimen  was  found 
for  the  missing  part,  and  I  doubt  not  that  the  search  will  be 
successful. 

Relationship^. — From  the  above  description  and  figures  it  is 
evident,  I  think,  that  the  relationships  of  Seymouria  are  not  very 
intimate  with  any  other  reptiles  known  from  the  Permian;  at 
least  any  that  are  tolerably  well  known.  In  the  skull  the  presence 
of  the  deep  otic  notch,  the  arrangement  and  number  of  the  temporal 
bones,  the  slender,  elongate  teeth,  longest  in  the  maxillae,  and  the 
shape,  all  differentiate  the  genus  widely  from  either  Diadectes  or 
Limnoscelis,  as  well  as  the  chief  forms  now  referred  to  the  Parioti- 
chidae,  and  also  from  the  known  foreign  forms.  The  speculation 
again  recurs  as  to  whether  or  not  the  temporal  vacuity  of  the  higher 
reptiles  may  not  have  arisen  by  the  prolongation  of  the  tabular 
angle  to  meet  the  quadrate  and  the  consequent  inclusion  of  the 
ear-notch.  Precisely  this  did  occur  in  some  of  the  contemporary 
temnospondyls.  Against  the  probability  of  this  is  the  fact  that 
the  quadrate  must  have  changed  somewhat  its  relations  with  the 
contiguous  bones;  although  as  a  matter  of  fact  we  do  not  know 
what  the  relations  of  the  quadrate  were  in  any  temnospondyl.  I 
do  not  think  that  this  would  be  impossible,  since  I  cannot  under- 
stand the  condition  in  Cacops  and  Dissorophus,  unless  the  flat 
process  bordering  the  posterior  bar  in  front  is  really  the  quadrate. 
However,  speculations  on  this  subject  are  premature.  Among  the 
Cacops  material  that  has  been  recovered  since  my  description  of 
the  genus  was  published  are  not  less  than  eight  good  skulls,  and 
there  are  doubtless  as  many  more  yet  to  be  recovered.  It  will  be 
strange  if,  from  among  all  this  material,  the  detailed  structure  of  the 
skull  is  not  finally  determined.  The  transfer  of  the  ear-cavity 
from  the  inclosed  opening  in  Cacops  to  a  place  back  of  the  vacuity  is, 
however,  quite  another  matter. 

In  any  event  it  is  certainly  very  remarkable  that  this  cotylosaur 
reptile  with  all  its  other  strange  amphibian  affinities  should  mimic 


64  AMERICAN  PERMIAN  VERTEBRATES 

so  closely  the  temporal  structure  of  the  real  amphibians,  while, 
on  the  other  hand,  real  temnospondyls  should  mimic  equally 
curiously  the  temporal  condition  of  the  higher  reptiles. 

Of  the  skeleton  back  of  the  skull  the  structure  is  largely  primi- 
tive both  in  the  pectoral  girdles  and  limbs  and  the  vertebrae,  which 
approach  those  of  the  temnospondyls  more  closely  than  do  those  of 
any  other  known  reptile.  The  absence  of  the  cleithrum  differ- 
entiates the  form,  though  not  widely,  from  Diadectes,  Limnoscelis, 
and  Pareiasaurus.  The  pectoral  girdle  offers  nothing  distinctive. 
The  presacral  vertebrae  differ  widely  from  those  of  Limnoscelis, 
Diadectes,  and  Pareiasaurus  in  the  almost  entire  absence  of  dorsal 
spines,  and  the  great  lateral  expansion  of  the  arches,  agreeing 
much  better  with  those  of  Labidosaurus.  Indeed,  the  vertebrae 
of  this  last  genus  are,  in  their  general  characters,  so  similar  that 
they  have  been  confused.  Nor  is  there  anything  distinctive  in 
the  pelvis;  it,  too,  is  of  the  " old-fashioned "  type.  In  the  limbs, 
however,  we  get  certain  apparent  resemblances  that  would  seem 
to  ally  the  genus  with  Diadectes  and  Limnoscelis,  but,  as  I  have 
stated  elsewhere,  I  have  little  faith  in  the  genetic  value  of  these 
characters.  I  believe  they  are  more  of  an  adaptive  nature.  Not 
only  do  the  limbs  resemble  those  of  Diadectes  and  Limnoscelis  more 
than  those  of  Labidosaurus,  but  this  resemblance  extends  to  the 
temnospondylous  amphibians  as  well,  especially  Eryops,  in  the 
short  legs,  short,  thickset  mesopodials,  broad  feet,  enormous 
humeral  entocondyle,  the  presence  of  an  ectepicondylar  process, 
very  large  adductor  crest,  and  enormous  digital  fossa  of  the  femora, 
etc.,  as  well  as  the  general  absence  of  condylar  ossifications — for 
in  all  these  forms  the  joints  were  formed  largely  by  cartilage 
which  never  ossified  and  the  sutures  remained  separated  longer 
and  more  completely  than  in  the  Pariotichidae. 

However,  it  is  very  much  of  a  question  whether  these 
resemblances  are  so  much  the  result  of  heredity  and  relationships 
as  of  adaptive,  parallel,  or  convergent  evolution.  We  have  been 
speculating  on  the  presumption  that  the  known  temnospondylous 
amphibians  like  Cacops,  Eryops,  Euchirosaurus,  are,  if  not  the 
actual  ancestors  of  the  reptiles,  their  first  or  second  cousins.  But 
this  presumption  is,  in  my  opinion,  quite  unjustified.  Moodie 


REPTILIA:  SEYMOURIA 


FIG,  22. — Seymouria  bayhrensis.     Skeleton,  from  above,  a  little  less  than  one- 
third  natural  size. 


66  AMERICAN  PERMIAN  VERTEBRATES 

has  urged  that  the  reptiles  arose  from  the  Microsaurs — that  is,  the 
Microsauria  as  usually  accepted — but  while  I  do  not  agree  with 
him  I  do  believe  that  he  comes  nearer  to  the  real  truth  than  is  the 
belief  that  reptiles  have  arisen  from  the  known  types  called  tem- 
nospondyli.  The  divergence  of  the  reptilian  stem  must  have 
occurred  early,  in  Pennsylvanian  if  not  Mississippian  times,  and 
what  we  have  in  the  Permian,  or  even  Permo-Carboniferous  beds 
of  Texas,  Illinois,  France,  and  elsewhere  are  the  modified,  perhaps 
very  much  modified,  descendants  of  these  early  divergent  phyla. 
The  view  of  Osborn  that  the  Cotylosauria  were  the  primitive 
reptiles  from  which  all  modern  forms  have  arisen  has  been 
doubtfully  accepted;  and  his  conclusion  that  the  reptilia  are 
divisible  into  two  subclasses,  the  Diapsida  and  Synapsida,  is  no 
longer  received  by  students  of  the  reptilia.  At  the  beginning  of 
the  Permian  or  even  earlier  we  have,  as  is  well  known,  at  least  four 
divergent  phyla  of  reptiles,  the  Cotylosauria,  the  Theromorpha  or 
therocrotaphic  forms,  the  Proganosauria,  with  aquatic  adaptions, 
and  the  Proterosauria  or  double-arched  forms.  It  is  a  very  inter- 
esting fact  that  the  chief  divergences  in  all  these  phyla  are  found 
in  the  temporal  region  of  the  skull.  The  pectoral  and  pelvic 
girdles,  the  vertebrae,  and  the  limbs  even,  differ  less  among  them  all 
than  do  they  in  some  later  orders  of  reptiles;  we  surely  will  find 
greater  modifications  among  the  modern  Squamata.  Did  we  not 
know  the  skulls  of  any  of  these  forms  we  would  have  little  cause 
to  separate  them  ordinally.  The  chief  differences  in  the  skull 
consists  of  the  absence  or  presence  of  one  or  more  vacuities  in  the 
temporal  region.  I  still  believe  with  Cope,  Woodward,  and  Osborn 
that  these  temporal  characters  are  the  most  crucial  ones  in  reptilian 
taxonomy.  And  yet  were  such  characters  as  those  of  Cacops  or 
Dissorophus  and  Trematops  to  be  found  among  reptiles,  we  would 
probably  accept  them  as  of  ordinal  value.  Among  the  cotylosaurs 
we  see  a  considerable  divergence  in  the  known  forms.  The  presence 
of  a  vestigial  cleithrum  in  some  cotylosaurs  and  some  theromorphs 
attests  a  not  very  remote  common  ancestry,  and  this  ancestry 
could  not,  of  course,  have  been  any  of  the  known  Microsauria,  since 
a  bone  or  organ  once  lost  never  reappears,  even  as  a  vestige. 
Furthermore,  Araeoscelis,  which  is  now  known  definitely  to  possess 


REPTILIA:  SEYMOURIA  67 

a  single  large  temporal  vacuity  and  foot  structure  not  unlike  that 
of  Varanosaurus,  was  an  animal  which  had  diverged  in  other 
respects  widely  from  its  contemporary  reptiles.  It  had  developed 
an  ectepicondylar  foramen,  and  had  become  a  very  swift-moving 
reptile. 

In  summation:  The  evolution  of  the  land  vertebrates  had 
developed  so  far  by  the  close  of  Carboniferous  times  that  reptiles 
of  considerable  diversity  of  habits  and  structure  had  arisen,  and 
it  would  be  unreasonable  to  suppose  that  the  temnospondyls  and 
cotylosaurs  were  exceptions,  that  they  still  retained  their  primitive 
characters  unchanged  or  almost  unchanged;  that  the  many  resem- 
blances between  such  creatures  as  Diadectes,  Seymouria,Limnoscelis, 
and  Eryops  were  the  result  of  heredity  rather  than  adaptive 
evolution.  We  have  been  deceived  time  without  end,  and  are 
yet  often  deceived  in  every  group  of  animal  and  vegetable  life  by 
resemblances  which  we  impute  to  heredity — that  is,  to  blood  rela- 
tionships— rather  than  to  adaptations  to  like  environmental  condi- 
tions. Of  course,  it  will  be  conceded  that  animals  whose  habits 
and  environments  have  changed  little  have  probably  not  changed 
their  structure  greatly.  The  marsh  turtles  have  continued  for 
millions  of  years  with  not  very  great  modifications  of  their  skeletal 
structure;  and  I  do  not  wish  to  say  that  all  the  resemblances 
between  Diadectes  and  Eryops,  for  instance,  are  necessarily  of 
adaptive  origin,  but  simply  that  we  have  many  more  facts  to  learn 
before  we  can  say  that  they  are  of  genetic  origin.  The  most  that 
we  can  expect  to  discover  in  the  Permian  fauna  are  the  ways  in 
which  the  evolution  of  the  reptiles  from  the  amphibians  has  occurred ; 
to  discover  archaic  forms  that,  one  by  one,  bridge  over  the  class 
differences  between  the  amphibians  and  reptiles.  And  in  this  we 
have  been  very  successful;  there  is  scarcely  a  detail  in  the  whole 
structure  of  the  reptiles  whose  origin  is  yet  inexplicable;  dis- 
tinguishing characters,  one  by  one,  have  been  completely  or  largely 
broken  down,  but  we  have,  nevertheless,  not  yet  found  a  creature 
about  which  there  is  doubt  as  to  its  position  in  the  two  classes 
when  fully  known. 


68  AMERICAN  PERMIAN  VERTEBRATES 

Family  Pariotichidae 
Cope,  Proc.  Amer.  Phil.  Soc.,  631,  1883. 

Reptiles  of  small  to  moderate  size,  with  a  large,  pointed  head, 
short  legs  and  tail.  Skull  roughened,  narrowed  in  front  of  the 
orbits;  either  tabulare  or  supratemporal  absent,  sometimes  both; 
a  dermoccipital  always  present;  occipital  condyle  rounded.  Teeth 
implanted  in  two  or  more  rows  on  maxillae,  one  or  more  on  mandi- 
bles. Presacral  vertebrae  twenty-three  or  twenty-four  in  number, 
the  arches  low,  but  not  transversely  expanded,  the  spines  low  and 
small;  two  sacral  vertebrae.  Dorsal  ribs  with  expanded  proximal 
end,  their  articulation  continuous  from  the  intercentral  space  to 
diapophysis ;  weak  or  absent  in  lumbar  region ;  the  anterior  dorsal 
ribs  distally  expanded  (in  all  ?).  Slender  ventral  ribs  are  present. 
No  clei thrum  in  pectoral  girdle.  Limb  bones  with  well-developed 
articular  surfaces;  digital  fossa  of  femur  not  elongate;  the  adductor 
ridge  not  prominent;  tibiale  and  fibulare  large;  front  feet  pente- 
dactylate;  phalangeal  formula  apparently  reduced. 

The  above  definition  is  based  exclusively  on  Captorhinus  and 
Labidosaurus ;  I  have  never  studied  closely  either  Isodectes  or 
Pariotichus.  The  former  genus  I  believe  will  be  found  quite 
distinct;  if  the  latter  is  also,  it  must  retain  the  family  name  Parioti- 
chidae and  another  be  chosen  for  Captorhinus  and  Labidosaurus. 
All  the  species  which  Cope  referred  to  Pariotichus,  save  the  typical 
one,  are  now  known  to  be  much  more  closely  related  to  the  geno- 
type of  Captorhinus  (C.  angusticeps]  and  must  be  referred  to  that 
genus. 

CAPTORHINUS 
Cope,  Proc.  Amer.  Phil.  Soc.,  XXXIV,  443,  1896. 

?  Captorhinus,  sp.     Plate  XXX,  Figs.  6,  7. 

A  single  femur  found  in  the  Craddock  bone-bed  shows  such 
decisive  pariotichid  characters  that  there  can  be  no  doubt  of  its 
relationships.  In  size  it  is  intermediate  between  that  of  the  smaller 
forms  of  Labidosaurus  and  the  larger  forms  of  Captorhinus,  but,  of 


REPTILIA:  CAPTORHINUS  69 

course,  its  specific  identity  cannot  be  determined  from  a  single 
specimen  and  the  few  associated  vertebrae  found  in  the  bed.  The 
figures  will  show  sufficiently  well  these  characters  and  the  bone 
does  not  need  further  description.  In  Plate  XXIV,  Figs.  8-10,  I 
give  several  illustrations  of  the  femur  of  Labidosaurus  hamatus, 
with  which  the  Craddock  specimen  may  be  compared. 

?  Captorhinus  illinoiensis,  n.  sp.     Plate  XXIV,  Figs.  5,  6,  7. 

A  well-preserved  femur  among  the  Gurley  type  collections  from 
the  Illinois  bone-bed  is  shown  in  the  cited  figures. 

Its  resemblance  is  so  great  to  the  femora  mentioned  above,  in 
the  small  digital  fossa,  the  protuberant  trochanter,  the  well-ossi- 
fied articular  extremities,  and  especially  in  the  shape  of  the  lower 
articular  surface,  that  I  have  little  doubt  the  bone  belongs  to  some 
undetermined  species  of  a  true  Pariotichid,  a  group  never  before 
recognized  from  these  beds.  It  is  true  that  no  vertebrae  of  the 
peculiar  pariotichid  type  have  been  recognized  from  this  horizon. 
Certainly  the  femur  does  not  belong  with  Clepsydrops,  as  the  genus 
is  now  recognized,  where  Case  has  located  it  and  figured  in  his 
Pelycosauria,  Plate  V,  Fig.  7. 


Class  REPTILIA 
Order  THEROMORPHA 

Cope,  Amer.  Nat.,  XII,  829,  1878;  Proc.  Amer.  Phil.  Soc.,  38;  Proc.  Amer. 
Assoc.  Adv.  Science,  XXXIII,  471,  1885. 

Crawling  reptiles  of  small  or  large  size,  carnivorous  or  herbivo- 
rous in  habit,  with  a  single,  lateral  temporal,  vacuity.  A  dermoc- 
cipital  bone  present,  but  the  identity  and  relations  of  the  other 
temporal  elements  unknown  or  in  dispute.  A  septomaxillary 
probably  always  present;  lachrymal  (adlachrymal ,  postnarial) 
not  reaching  the  nares  (Edaphosaurus?).  Teeth  thecodont  or 
acrodont,  inserted  on  premaxillae,  maxillae,  palatines,  pterygoids, 
and  sometimes  the  splenials.  Vertebrae  deeply  biconcave  or 
notochordal,  from  twenty-four  to  twenty-seven  or  more  in  front 
of  the  sacrum;  two  or  three  sacrals;  tail  moderately  long.  Inter- 
centra  always  present.  Ribs  double-headed  throughout,  attached 
to  diapophysis  and  intercentral  space;  slender  ventral  ribs  some- 
times present.  Cleithrum  rarely  present;  clavicles  and  inter- 
clavicles  large,  the  latter  with  a  long  stem;  no  ossified  sternum. 
Coracoid  fused  with  scapula;  posterior  coracoid  bone  forming 
only  the  posterior  part  of  the  glenoid  cavity,  sometimes  unossified. 
Pelvis  plate-like,  rarely  with  a  small,  median,  puboischiadic 
vacuity.  Humerus  with  entepicondylar,  rarely  also  with  ectepi- 
condylar,  foramen;  usually  widely  expanded  at  the  extremities. 
Carpus  with  four  proximal  bones,  two  centralia,  and  four  or  five 
carpalia.  Tarsus  with  dilated  tibiale  and  fibulare;  no  separate 
intermedium;  a  single  centrale  and  five  tarsalia.  Phalangeal 
formulae,  2,  3,  4,  5,  4  (3).  No  dermal  ossifications. 

The  term  Pelycosauria  was  proposed  by  Cope  for  a  suborder 
of  Rhynchocephalia,  based  upon  Clepsydrops  and  Dimetrodon, 
and  published  for  the  first  time  (fide  Cope)  in  Paleontological 
Bulletin,  No.  29,  on  May  8,  1878.  Later,  in  the  American  Natural- 
ist of  the  same  year  for  December,  he  proposed  the  ordinal  term 

70 


REPTILIA  :   THEROMORPHA  71 

Theromorpha  to  include  the  two  suborders  Pelycosauria  and 
Anomodontia,  the  latter  term  used  in  a  wider  sense  than  is  now 
recognized.  As  a  usual  thing,  priority  is  not  much  respected 
in  the  use  of  classificatory  terms  above  the  genus.  As  proposed 
by  Cope  the  suborder  Pelycosauria  was  coextensive  with  the 
family  Clepsydropidae,  to  which  after  was  added  the  Poliosauridae 
by  Case.  If  we  extend  the  term  to  include  all  the  therocrotaphic 
reptiles  from  the  Permian  of  America,  from  Naosaurus  to  Araeo- 
scelis,  as  an  order  it  displaces  the  ordinal  term  Theromorpha, 
unless  the  order  be  retained  to  include  the  African  forms  grouped 
by  Broom  in  his  order  or  superorder  Therapsida;  in  the  latter  case 
it  would  take  precedence  over  all  others.  If,  later,  it  is  shown 
that  all  the  American  forms  are  coherently  distinguishable  by 
valid  group  characters  from  the  Therapsida,  and  provided  that 
no  higher  rank  is  given  to  the  whole  assemblage  than  an  order, 
the  American  forms,  by  the  extension  of  the  boundaries  of  the 
suborder  Pelycosauria,  may  be  distinguished  from  the  African 
suborder  Therapsida.  But  there  is  little  probability  of  any 
unanimity  of  opinion  in  this.  Broom  insists  that  the  groups 
Therocephalia,  Dromasauria,  etc.,  are  at  least  of  subordinal  value, 
and  certainly  the  differences  between  the  phytophagous  Casea 
and  Dimetrodon  are  as  great  as  between  the  Dromasauria  and  the 
Therocephalia,  each  of  which  would  likewise  be  entitled  to  subordinal 
distinction. 

It  is,  however,  quite  impossible  to  satisfactorily  distinguish 
all  the  imperfectly  known  forms  at  present,  and  as  it  is  quite 
certain  there  are  many  more  therocrotaphic  forms  to  be  discovered 
in  Africa  and  North  America,  to  say  nothing  of  the  forms  that  may 
be  expected  from  other  parts  of  the  world,  it  seems  most  expedient 
to  resuscitate  the  term  Theromorpha  for  our  American  genera  at 
least;  and  as  nothing  much  is  to  be  gained  in  the  present  state  of 
our  ignorance  by  dividing  our  American  genera  into  various 
suborders,  the  term  Pelycosauria  may  be  held  in  abeyance,  or  used 
only  to  distinguish  the  long-spined  theromorphs. 

I  recognize,  then,  the  following  groups  of  American  theromorphs: 
Sphenacodontidae  (Clepsydropidae),  Poliosauridae,  Edaphosauri- 
dae,  Caseidae,  and  Araeoscelidae. 


72  AMERICAN  PERMIAN  VERTEBRATES 

Family  Sphenacodontidae 

Marsh,  Amer.  Jour.  Science,  411,  May  3,  1878;  Clepsydropidae  Cope,  Proc. 
Amer.  Phil.  Soc.,  XVII,  529  (published  May  8,  fide  Cope,  as  Paleonto- 
logical  Bulletin,  No.  29). 

Carnivorous  reptiles  with  high  skull,  anisodont  teeth,  and  greatly 
elongated  dorsal  spines.  Clei thrum  (always?)  present;  sacrum 
with  three  vertebrae;  pubes  with  greatly  elongated,  plate-like 
expansion  in  front.  Of  moderate  to  large  size. 

Under  the  assumption  that  Sphenacodon  has  elongated  dorsal 
spines,  of  which,  however,  there  is  no  evidence  and  much  improb- 
ability, the  family  name  Clepsydropidae  is  quite  synonymous 
with  Sphenacodontidae.  If  Sphenacodon  has  only  moderately 
elongated  spines,  and  a  general  identity  of  its  other  characters  with 
Dimetrodon  or  Clepsydrops,  it  may  perhaps  require  the  modifica- 
tion of  the  characters  given  above;  or  the  family  name  may  be 
recognized  as  distinct. 

CLEPSYDROPS 
Cope,  Proc.  Acad.  Nat.  Sciences,  Philadelphia,  407,  1875. 

The  genotype  specimen  of  this  genus  consists  of  a  series  of  iso- 
lated vertebral  centra  from  the  so-called  Permian  of  Illinois. 
In  my  opinion  vertebral  centra  are  wholly  unreliable  in  this  order 
as  generic  types,  to  say  nothing  of  species;  they  may  be  proven 
eventually  to  belong  to  either  of  several  related  genera.  How- 
ever, Cope  in  1878  referred  a  species  from  the  Permian  of  Texas 
to  the  same  genus,  which  he  called  C.  natalis,  and  it  is  from  this 
homotype  that  all  the  distinctive  characters  of  the  genus  have  so 
far  been  derived.  It  is  very  probable,  merely  as  a  matter  of 
exclusion,  that  Cope  correctly  identified  his  Texas  genus  with 
Clepsydrops,  since  we  know  that  the  limb  bones  associated  with  C. 
natalis  do  closely  agree  with  limb  bones  found  associated  with  the 
type,  but  not  anatomically  so,  from  the  Illinois  bone-bed.  And  here 
is  perhaps  one  of  the  best  arguments  against  the  strict  rulings  of 
the  international  committee  on  nomenclature.  If,  fifty  years  hence, 


REPTILIA:  CLEPSYDROPS  73 

as  is  not  unlikely,  it  is  definitely  proven  that  the  original  types  are 
equally,  perhaps  more,  characteristic  of  a  genus  distinct  from  that 
including  the  Texas  species  referred  to  Clepsydrops,  it  would  be  in 
defiance  of  common  sense  to  introduce  a  new  name  for  the  latter 
because  the  identity  of  its  type  is  in  dispute. 

Clepsydrops  natalis  (?)  Cope,  Proc.  Amer.  Phil.  Soc.,  XVII,  509,  529,  1878; 
Case,  Pelycosauria,  42,  90,  Pis.  IV,  V,  VI,  1908. 

Among  the  material  from  the  Craddock  bone  quarry  there  are 
numerous  limb  bones  and  other  parts  of  the  skeleton  which  agree 
so  closely  with  the  descriptions,  and  especially  with  the  figures,  of 
this  species  as  given  by  Case,  that  I  believe  there  can  be  little 
doubt  of  their  correct  determination.  They  are,  like  all  other 
specimens  from  this  quarry,  in  such  excellent  preservation  that  I 
have  given  figures  of  many  of  them  and  rather  full  descriptions. 
That  they  all  belong  in  the  same  species  is  doubtful,  however. 

Femora. — Two  forms  of  femora  are  shown  in  Plate  XXX, 
Figs,  i,  2,  and  Plate  XXXII,  Fig.  i.  The  upper  extremity  is 
truncate,  the  surface  subcrescentic  in  outline,  much  narrower  in 
the  femur  shown  in  Fig.  i  than  in  that  of  Fig.  2.  The  trochanteric 
ridge  is  high  up;  the  digital  fossa  shallow.  The  distal  extremity 
is  slightly  convex  dorsoventrally;  the  outer  condyle  is  usually 
much  broader;  both  the  popliteal  and  extensor  grooves  are  shallow. 
The  stouter  femur  has  decidedly  thicker  ends  and  is  a  little  wider 
than  the  other.  The  shaft  is  oval  in  cross-section,  and  is  more 
slender  in  the  one  shown  in  Fig.  i  than  that  of  Fig.  2.  These 
differences  seem  too  great  for  specific  identity.  The  slender 
femur  may  be  provisionally  designated  as  Clepsydrops  A.;  the 
more  robust  as  B.  In  addition  to  the  larger  femora  of  nearly 
uniform  length  there  are  numerous  ones  hi  the  collection,  one  of 
which  is  shown  in  Plate  XXX,  Fig.  3,  of  much  smaller  size,  agree- 
ing better  with  Clepsydrops  A.,  save  that,  as  would  be  expected 
of  juvenile  bones,  the  ends  are  less  well  ossified. 

Tibia. — A  left  tibia,  which  in  size  seems  to  agree  well  with  the 
larger  femora,  is  shown  in  Plate  XXX,  Fig.  10,  and  may  be 
referred  to  one  or  the  other  of  the  forms  represented  by  the  femora, 
perhaps  better  with  the  more  slender  one;  it  is  very  perfect. 


74  AMERICAN  PERMIAN  VERTEBRATES 

That  it  belongs  with  the  femora  seems  probable  because,  not  only 
agreeing  in  size,  it  shows  the  same  lack  of  articular  ossification  so 
characteristic  of  this  genus.  The  bone  is  much  curved;  the 
shaft  slender;  the  upper  extremity  much  expanded.  The  outer 
border  is  very  deeply  concave,  as  is  also  the  posterior.  The  upper 
end  is  gently  convex,  with  angular  margins;  it  is  elongate,  with  a 
small  anterior  projection.  The  lower,  sharply  truncate  end  is 
obliquely  ovate  in  shape;  the  posterior  inner  part  narrower. 

A  smaller  tibia,  about  three-fifths  the  length  of  the  larger  one, 
agrees  in  general  characters,  save  that  the  cnemial  convexity  is 
less  pronounced.  It  probably  belongs  with  femora  referred  to 
Clepsydrops. 

The  fibula  shown  in  Plate  XXX,  Fig.  1 1 ,  in  much  probability 
belongs  with  Clepsydrops,  but  this  is  not  at  all  certain.  The 
shaft  is  only  moderately  slender;  the  lower  end  is  much  dilated, 
and  the  articular  surface  is  not  at  all  oblique  to  the  long  axis  of 
the  bone,  as  in  the  same  plate,  Fig.  9.  Various  carpal  and  tarsal 
bones  preserved  evidently  belong  with  this  genus,  and  especially 
the  astragalus  shown  in  plate  XXXII,  Fig.  9,  and  the  calcaneum 
shown  in  Plate  XXXI,  Fig.  10,  and  Plate  XXXII,  Fig.  n. 

Humerus  (Plate  XXXI,  Fig.  3). — There  are  several  humeri 
which  agree  well  with  those  referred  to  C.  natalis  by  Case  and  Cope, 
and  doubtless  of  the  same  species  as  one  or  the  other  of  the  large 
femora  figured  in  Plate  XXX.  Like  the  femora,  the  extremities 
were  largely  cartilaginous  in  life,  the  condyles  undeveloped.  The 
lateral  process  reaches  about  one-third  the  length  of  the  bone; 
the  plane  of  the  inner  side  above  is  at  about  sixty  degrees  with 
that  of  the  lower  end.  The  entepicondylar  foramen  is  large,  and 
is  remote  from  the  border.  The  upper  angles  of  the  cartilaginous 
borders  of  the  condyles  are  nearly  opposite  each  other,  and  are 
low  down,  the  two  sides  of  the  bone  nearly  symmetrical  below  the 
lateral  process. 

With  the  half-dozen  large  humeri  there  are  as  many  more  of 
small  size,  a  half  or  less  the  length  of  the  larger,  which  doubtless 
are  of  young  animals;  one  is  shown  in  Plate  XXX,  Fig.  5.  They 
agree  in  general  with  the  larger  ones,  except  that  the  shaft  is  more 
slender  and  the  ends  less  well  ossified,  the  lateral  process  is  rela- 


KEPT  I  LI  A  :  CLEPSY  DROPS  75 

lively  smaller  and  the  entepicondylar  process  is  relatively  much 
larger.  They  also  agree  well  with  the  specimens  referred  to 
Clepsydrops  from  Illinois. 

Ilium. — Because  of  the  number,  shape,  and  size  I  refer  several 
ilia  to  this  genus  and  species,  one  of  which  is  shown  in  Plate  XXXI, 
Fig.  2.  It  has  a  rather  narrow  and  elongated  posterior  process. 
The  upper  border  is  much  higher  and  thinner  in  front  than  behind, 
the  hind  extremity  with  a  small  cartilaginous  surface.  The  inner 
side  shows  marked  rugose  surfaces  for  two  sacral  ribs;  there  may 
have  been  a  third.  The  outer  side  has  a  distinct  curved  ridge  for 
muscular  attachment. 

Ischium. — A  well-preserved  ischium,  because  of  its  size,  doubt- 
less belongs  with  one  or  the  other  of  the  ilia  like  that  just  described ; 
it  is  shown  in  Plate  XXXI,  Fig.  4.  It  is  of  the  typical  pelyco- 
saurian  shape  with  sharp  cartilaginous  borders;  the  blade  convex 
on  the  outer,  concave  on  the  inner,  side,  with  a  thick  border  for 
the  acetabulum.  Several  small  or  very  small  ischia  of  the  same 
shape  are  among  the  collection,  but  as  the  ischia  of  the  Permian 
reptiles  in  general  are  very  uncharacteristic  bones,  they  can  only 
be  referred  to  this  genus  doubtfully. 

Quadrate. — A  very  complete  quadrate,  which  because  of  its 
size  may  be  provisionally  referred  to  this  genus,  is  shown  in  Plate 
XXXI,  Figs.  5,  6.  The  roughened  elongated  surface  on  the 
posterior  side  for  union  with  the  cranial  bones  is  very  conspicuous. 
The  condylar  surfaces  are  perfect;  the  outer  elongate  part  separated 
from  the  inner,  more  triangular  one,  by  a  deep  groove. 

Articular. — Several  articular  bones  in  perfect  preservation  may 
belong  with  this  genus.  I  figure  one  in  Plate  XXXI,  Figs.  8,  9, 
showing  the  characteristic  form  of  the  bone;  it  is  of  interest  as 
proving  the  absence  of  an  anterior  or  prearticular  process  to  the 
bone;  that  is,  the  prearticular  bone  is  distinct. 


NAOSAURUS 

Of  the  real  skeletal  structure  of  Naosaurus,  notwithstanding  the 
various  restorations  that  have  been  published,  very  little  is  known 
aside  from  the  precaudal  vertebrae,  the  pelvis,  and  perhaps  the 


76 


AMERICAN  PERMIAN  VERTEBRATES 


humerus.  The  skull,  pectoral  girdle,  and  limbs  have  all  been 
assumed  to  be  like  those  of  Dimetrodon,  which  have  been  used  in 
the  restorations.  But  I  am  very  skeptical  indeed  of  the  legitimacy 


FIG.  23. — Naosaurus,  or  new 
genus.  Right  femur,  tibia,  and  fibula, 
ventral  side,  two-fifths  natural  size. 


FIG.  24.  —  Dimetrodon  incisivus 
Cope.  Right  femur,  tibia,  and  fibula, 
ventral  side,  two-fifths  natural  size. 


of  this  assumption.  I  believe  that  when  the  skeleton  is  fully 
known  it  will  prove  to  be  very  unlike  that  of  Dimetrodon.  Case 
has  been  inclined  to  the  belief  that  Naosaurus  is  a  synonym  of 


REPTILIA:  NAOSAURUS  77 

Edaphosaurus,  known  only  from  the  skull,  and  I  myself  would  be 
inclined  to  this  belief,  were  it  not  that  the  two  known  specimens  of 
Edaphosaurus  are  altogether  too  small  to  go  even  with  the  smallest 
of  the  known  specimens  of  Naosaurus.  On  the  west  side  of  Hog 
Creek,  near  Seymour,  Texas,  I  found,  two  years  ago,  a  very  perfectly 
preserved  specimen,  consisting  of  the  right  femur,  tibia,  and  fibula 
and  part  of  the  astragalus,  all  in  close  articulation,  bones  unlike 
anything  hitherto  known  from  Texas.  I  am  much  inclined  to 
think  that 'they  really  belong  with  Naosaurus,  though  that  con- 
clusion is  reached  merely  by  exclusion.  I  give  herewith  figures 
of  these  bones,  ventral  views,  in  contrast  with  like  views  of  the 
corresponding  bones  of  Dimetrodon  incisivus,  made  from  an  unusu- 
ally perfect  specimen  from  the  Craddock  bone-bed,  all  drawn  to  the 
same  scale.  It  will  be  observed  that  the  femur  is  much  more  slender 
than  that  of  Dimetrodon,  the  digital  fossa  is  deeper  and  longer, 
the  trochanter  more  prominent,  the  adductor  ridge  also  more  promi- 
nent and  continued  half-way  to  the  outer  condyle,  instead  of  end- 
ing with  the  trochanteric  eminence.  The  lower  extremity  is  more 
gradually  dilated,  though  the  distal  articular  surfaces  are  much 
alike.  The  tibia  and  fibula  are  characterized  by  their  remarkable 
shortness  and  stoutness,  so  short  and  stout  that,  had  they  been 
found  isolated,  they  would  have  been  referred  to  the  Eryopidae  or 
Diadectidae.  The  fibula  in  contrast  with  that  of  Dimetrodon, 
here  for  the  first  time  figured,  is  very  different,  though  having  the 
same  general  characters  and  articular  surfaces;  its  shaft  is  very 
stout  and  its  lower  end  much  expanded.  The  tibia  has  its  ends 
rather  larger  than  those  of  Dimetrodon,  while  scarcely  two-thirds 
as  long;  its  shaft  is  stouter.  That  the  leg  belongs  to  a  zygocro- 
taphic  reptile  I  am  assured  because  of  its  general  resemblance 
to  that  of  Dimetrodon,  but  that  the  habits  of  the  animal  were 
very  unlike  those  of  Dimetrodon  is  equally  evident.  However, 
there  is  certain  evidence  of  a  still  unnamed  reptile  from  these  beds, 
found  in  the  Craddock  bone-bed,  of  large  size,  but  with  slender 
jaws,  and  this  leg  may  possibly  belong  with  that  form,  which 
will  be  described  and  figured  later.  Should  the  form  prove  new, 
as  it  undoubtedly  is  if  not  Naosaurus,  it  may  be  known  as  Brachy- 
cnemius  dolicjtomerus  g.  s.  nov. 


78  AMERICAN  PERMIAN  VERTEBRATES 

SPHENACODON 

Sphenaco don  ferox  Marsh,  Amer.  Jour.  Science,  XV,  410,  May  3, 
1878. 

In  the  present  genus  the  anterior  teeth  are  somewhat  like  those  of  the 
reptile  described  above,  but  the  posterior,  or  more  characteristic  ones,  are 
totally  different.  The  crowns  are  much  compressed,  and  have  very  sharp  cutting 
edges,  without  crenulations.  In  the  present  species  the  carnivorous  teeth  are 
crowded  together,  and  the  crowns  placed  slightly  oblique,  and  twisted.  The 
jaws  were  comparatively  short  and  massive.  The  rami  of  the  lower  jaws  were 
apparently  united  by  cartilage  only,  and  the  symphysis  was  short.  The 
vertebrae  are  deeply  biconcave. 

Measurements  from  the  type  of  this  species  are  as  follows : 

Length  of  dentary  bone 150  mm. 

Space  occupied  by  teeth 130 

Extent  of  four  anterior  caniniform  teeth 25 

Extent  of  twenty  compressed  teeth 105 

Height  above  jaw  of  second  lower  tooth 15 

Depth  of  dentary  bone  at  symphysis 26 

Height  of  crown  of  compressed  tooth 8 

Transverse  diameter 4 

This  reptile  was  about  six  feet  in  length,  and  carnivorous  in  habit.  Its 
remains  are  from  the  same  locality  in  New  Mexico  that  yielded  those  of 
Nothodon. 

The  type  specimen  is  shown  natural  size  in  Plate  XXXIV, 
Fig.  i,  a  left,  incomplete  dentary.  The  second  tooth,  while  agree- 
ing with  his  measurements,  is  incomplete;  the  fracture  is  evident, 
yet  apparently  Marsh  did  not  observe  it.  The  tooth  was  probably 
twice  the  length  shown  in  the  figure.  There  appears  also  to  have 
been  a  very  small  tooth  in  front,  of  which  only  a  slight  indication 
of  the  alveolus  remains.  That  this  specimen  is  the  holotype, 
aside  from  the  general  agreement  of  the  measurements,  is  assured 
by  the  fact  that  it  was  the  only  bone  in  the  entire  collection  which 
had  been  mended,  by  the  gluing  together  of  the  seven  separate 
pieces  of  which  it  was  composed.  And  there  is  no  other  specimen 
in  the  entire  collection  which  will  agree  with  his  description.  In 
immediate  association  with  this  dentary,  in  the  same  lot  and  collected 
with  it,  are  two  maxillae,  which  agree  in  size,  color,  and  condition  of 
preservation.  There  can  be  scarcely  a  doubt  but  that  they  belong 


REPTILIA  :  SPHENACODON  79 

with  the  same  individual  as  did  the  dentary  and  may  be  considered 
as  part  of  the  type.  These  were  the  only  specimens  in  the  lot 
studied  by  Marsh.  Later  finds  by  Baldwin  show  several  other 
mandibles  and  maxillae,  but  the  numerous  pieces  into  which  the}' 
were  broken  were  widely  scattered  through  the  collection.  They 
were,  if  seen  at  all  by  Marsh,  probably  not  attentively  examined. 
It  is  surprising,  however,  that  in  an  entire  collection  from  this 
horizon,  and  this  bone-bed,  a  collection  including  perhaps  hundreds 
of  vertebrae,  I  can  find  no  indications  of  long,  Dimetrodon-like  spines. 
Marsh  stated  that  the  vertebrae  are  deeply  biconcave,  but  the 
fact  is  that  not  a  single  vertebra  can  be  certainly  correlated  with  the 
type  specimen  or  species.  There  are  twenty-four  teeth  or  sockets 
for  teeth  in  the  dentary,  a  number  somewhat  under  the  usual  one 
in  Dimetrodon.  The  first  and  third,  as  preserved,  are  of  nearly 
equal  size;  they  are  longer  than  the  ones  following,  are  more 
pointed  and  convex  above.  The  second  tooth  in  life  was  probably 
twice  the  length.  The  remaining  teeth  are  of  nearly  equal  size, 
save  the  last  four,  the  roots  of  which  are  distinctly  smaller.  The 
fourth  and  the  sixth  have  each  a  distinctly  worn  facet  on  the  outer 
side,  which  fits  precisely  the  outer  facets  of  the  caniniform 
tooth  of  the  corresponding  maxilla.  In  the  left  maxilla  (Plate 
XXXVII,  Fig.  i),  there  are  two  smaller  teeth  in  front  of  the  very 
large  caniniform  tooth.  Back  of  this  tooth  there  is  a  cavity  on 
each  side,  apparently  for  a  tooth  of  considerable  size.  This  con- 
dition is  noted  by  Case  as  characteristic  of  the  Clepsydropidae, 
with  rare  exceptions;  in  another  dentary  of  smaller  size  in  the 
collection  the  alveolus  is  filled,  the  three  large  teeth  being  all  nearly 
of  one  size.  Back  of  this  cavity  there  are  twelve  teeth  or  cavities 
for  teeth.  They  are  all  of  a  slightly  larger  size  than  those  in  the 
dentary,  and,  with  the  caniniform  tooth  biting  in  the  place  shown 
by  the  worn  facets,  the  teeth  would  extend  back  of  the  lower  ones 
about  fifteen  millimeters.  The  whole  number  in  the  maxilla  was 
but  sixteen,  a  smaller  number  than  is  known  in  species  of  Dimetro- 
don. None  of  the  teeth  is  serrated  on  its  margins.  It  is  evi- 
dent from  the  position  of  the  anterior  process  in  front  of  the  first 
tooth  that  the  border  of  the  diastema  was  not  ascending.  The 
remainder  of  the  collection  obtained  later  by  Baldwin,  evidently 


8o  AMERICAN  PERMIAN  VERTEBRATES 

from  the  same  horizon,  and  some  at  least  from  the  same  "  bone- 
quarry/'  has  several  maxillae  and  mandibles  and  other  parts  of  the 
skull  of  this  same  genus,  and  apparently  this  same  species. 
Strangely,  however,  as  I  have  already  stated,  among  the  numerous 
vertebrae  accompanying  them  and  the  other  genera  I  can  find 
none  with  long  spines.  Such  vertebrae  as  have  been  restored 
have  rather  short  thin  spines,  resembling  those  of  Varanosaurus, 
etc.,  together  with  others  which  I  refer  to  Nothodon.  I  give  a 
figure  of  a  premaxilla  from  among  these  skulls.  For  the  descrip- 
tion of  limb  bones,  some  of  which  may  belong  with  this  genus,  see 
under  Ophiacodon. 

Family  Poliosauridae 

Case,  Pelycosauria,  18,  1908. 

Primitive  Pelycosauria  with  low,  flat,  acuminate  head,  sometimes  elongate, 
the  maxillary  with  straight  tooth  line.  One  or  more  teeth  at  the  anterior  end 
of  the  premaxillary  and  dentary,  and  one  or  more  teeth  in  the  maxillary 
enlarged  somewhat  above  the  others.  Maxillary  teeth  not  separated  from  the 
premaxillary  teeth  by  a  toothless  interval.  Vertebral  spines  low  and  the  neural 
arch  free  from  the  centrum  through  life  in  some  (Poliosaurus).  Abdominal 
scutes  present.  Sacrum  with  two  vertebrae.  Long-bodied  forms  with  long 
tail;  probably  aquatic. 

The  above  definition  by  Case  includes  the  most  essential  charac- 
ters of  this  family,  though  the  assumption  that  the  animals  were 
probably  aquatic  is  evidently  wrong,  and  the  separation  of  the 
neural  arches  in  Poliosaurus  is  not  a  family,  nor  even  a  generic, 
character,  since  I  doubt  not  it  was  due  always  to  age.  To  these 
characters  may  be  added,  as  based  chiefly  upon  the  skeletons  of 
Varanosaurus  described  further  on,  the  following: 

Twenty-seven  presacral  vertebrae  (which  number,  however, 
may  be  only  of  generic  value);  pubis  elongated  and  expanded 
anteriorly  as  in  Dimetrodon;  no  clei thrum;  the  lower  temporal 
arch  is  incomplete  below  in  some,  perhaps  all,  the  known  genera. 
To  this  family  belong  with  assurance  the  following  genera:  Polio- 
saurus, Ophiacodon,  T  hero  pleura,  Varanosaurus,  Poecilospondylus, 
and  other  known  yet  undescribed  forms.  It  is  very  doubtful 
whether  Elcabrosaurus  belongs  here,  or  indeed  whether  the  name  is 
not  a  synonym. 


REPTILIA  :  OPHIACODON  81 

OPHIACODON 
Marsh,  Amer.  Jour.  Science,  XV,  411,  May  3,  1878. 

Ophiacodon  mirus  Marsh,  loc.  clt. 

A  third  genus  of  reptiles  allied  to  the  last  described  [Sphenacodon]  is  indi- 
cated by  various  well-preserved  remains  from  the  same  locality.  The  teeth  are 
all  carnivorous  in  type,  conical  in  form,  and  all  are  similar.  Those  in  the 
anterior  part  of  the  jaws  are  recurved,  and  in  general  shape  resemble  those  of 
serpents.  The  rami  of  the  lower  jaws  were  united  only  by  cartilage.  The 
vertebrae  are  very  deeply  biconcave,  and  even  perforate,  and  the  intracentral 
bones  large.  In  the  present  species  the  teeth  are  nearly  smooth,  and  some- 
what compressed. 

The  following  measurements  indicate  the  size  of  this  reptile: 

Extent  of  anterior  sixteen  teeth  in  dentary 75  mm. 

Extent  of  anterior  five  lower  teeth 20 

Height  of  crown  of  fourth  lower  tooth 10 

Depth  of  lower  jaw  at  symphysis 15 

Extent  of  seven  anterior  maxillary  teeth 33 

Height  of  crown  of  first  maxillary  tooth 9 

Antero-posterior  diameter  of  crown 3 

This  species  was  about  as  large  as  those  described  above,  and  is  from  the 
same  geological  horizon  in  New  Mexico. 

The  type  specimen  of  this  genus  and  species,  a  mandible,  is 
figured  in  Plate  XXXI,  Fig.  3.  Some  of  the  long  teeth  had  been 
gummed  together  with  mucilage,  but  other  fragments  were  still 
separate,  and  yet  others  have  not  been  recovered.  Fragments 
of  an  upper  jaw  from  which  the  measurements  had  been  taken  I 
have  not  thought  necessary  to  figure.  In  addition,  I  find  three  or 
four  mandibular  bones  and  several  maxillae,  all  of  them  of  a 
somewhat  larger  size  than  is  the  type  specimen.  All  of  these 
specimens  are  from  among  the  original  collection  studied  by 
Marsh.  I  find  no  other  evidences  of  the  skull  among  the  material 
acquired  later. 

With  this  genus  I  associate  provisionally  a  considerable  number 
of  limb  bones  and  vertebrae  which  were  associated  with  the  type 
specimen,  including  five  humeri,  the  best  and  largest  of  which  I 
have  figured;  a  complete  radius  and  a  complete  ulna,  and  parts  of 
two  or  three  others  of  each  bone;  at  least  five  scapulae,  none  of 


82  AMERICAN  PERMIAN  VERTEBRATES 

which  has  been  restored  complete;  a  half-dozen  ilia,  of  which  one 
of  the  smallest  I  have  figured;  at  least  three  pubes,  and  as  many 
ischia,  none  of  which  has  been  made  complete;  five  femora,  four 
of  about  equal  size,  one  of  which  I  have  figured,  the  fifth,  though 
no  longer  and  resembling  the  others  in  shape,  is  a  distinctly  stouter 
bone;  six  tibiae  of  nearly  equal  size,  one  of  which  is  figured;  four 
fibulae  of  nearly  equal  size,  one  of  which  I  figure;  and  numerous 
hand  and  foot  bones,  many  of  which  probably  belong  with  this 
genus.  Besides  these  limb  bones  there  are  numerous  vertebrae, 
of  which  five  or  six  are  in  one  series,  with  the  intercentral  bones  in 
position,  probably  the  ones  referred  to  this  genus  by  Marsh.  I 
figure  an  isolated  one  from  the  later  collections. 

From  the  later  collections,  as  already  stated,  I  find  no  limb  or 
skull  bones  of  these  forms,  though  there  are  not  a  few  vertebrae 
with  short,  thin  spines.  Among  these  later  collections  there  are 
a  number  of  mandibles  and  maxillae  agreeing  quite  with  the  type 
of  Sphenacodon  ferox,  and  a  few  limb  bones  which,  though  incom- 
plete, seem  to  differ  in  their  greater  slenderness  and  more  Dime- 
trodon-like  form. 

I  refer  these  limb  bones  and  vertebrae  to  this  genus,  rather 
than  to  Sphenacodon,  because  they  agree  better  with  the  polio- 
saurid  than  the  clepsydropid  type,  though  their  positive  identity 
must  depend  upon  their  future  discovery  in  actual  juxtaposition. 

The  figures  of  the  typical  specimens  of  mandible,  together 
with  Marsh's  description,  will  render  the  skull  of  Ophiacodon 
easily  recognizable.  The  anterior  teeth  are  long  and  recurved,  and 
somewhat  flattened,  not  only  in  these  specimens,  but  also  in  impres- 
sions of  perfect  teeth  yet  preserved  in  the  matrix.  The  posterior 
teeth  are  almost  cylindrical  and  scarcely  at  all  compressed;  they 
are  all  shorter,  and  but  slightly  recurved.  Several  of  the  mandibles 
are  somewhat  larger  than  in  the  type  specimen.  The  mandible 
may  have  had  a  length  of  from  150  to  200  millimeters.  The 
specimens  indicate  a  relatively  slender  and  small  skull  of  the  polio- 
saurid  type,  too  small,  it  would  seem,  to  belong  with  some  of  the 
limb  bones,  were  it  not  there  is  similar  disparity  in  size  shown 
between  the  mandibles  and  limb  bones  in  the  specimens  of  Thero- 
pleura  retroversa  Cope  figured  by  Case  (Pelycosauria,  Plate  III) . 


REPTILIA  :  OPHIACODON  83 

As  stated,  there  are  numerous  vertebrae  in  the  collection  that 
have  the  general  characters  of  the  one  figured  in  Plate  XXXVIII, 
Fig.  3.  The  larger  part  of  the  vertebrae,  however,  have  not  yet 
been  restored  from  their  fragments,  and  it  is  quite  possible  that 
among  them  later  will  be  found  two  distinct  types;  one  of  them 
belonging  with  Ophiacodon,  the  other  with  Sphenacodon.  The 
centrum  of  the  posterior  dorsal  or  lumbar  vertebra  shown  in  the 
figure  is  rather  shorter  and  stouter  than  others;  it  has  a  thin 
keel  below.  '  The  co-ossified  rib  has  a  slender,  capitular  process, 
and  a  heavy  tubercular  one,  uniting  with  both  centrum  and  arch. 
The  rib,  broken  away  in  the  specimen,  was  probably  about  fifty 
millimeters  in  length.  The  spine  is  broad  and  flat,  with  thin 
edge;  its  height  is  less  than  four  times  the  diameter  of  the  centrum, 
though  rather  more  elongated  than  in  Varanosaurus.  Anterior 
dorsals  in  the  collection  have  similar  spines,  as  also  caudals,  and 
it  is  because  of  this  character  that  I  assign  the  vertebrae  to  Ophia- 
codon rather  than  to  Sphenacodon,  and  which  forces  the  conclusion 
that  the  genus  belongs  among  the  Poliosauridae. 

PECTORAL  GIRDLE  AND  EXTREMITY 

Clavicle. — There  are  numerous  clavicles  in  the  collection,  one 
of  the  most  complete  of  which  I  have  figured  in  Plate  XXXVI, 
Fig.  4.  It  is  a  rather  slender  bone,  only  moderately  expanded  at 
its  mesial  extremity.  The  outer  or  dermal  surface  of  this  part 
is  coarsely  striate.  This  clavicle  is  of  poliosaurid  type,  and  quite 
unlike  the  clepsydropid. 

Scapula. — There  are  six  or  eight  scapulae  in  the  type  collection, 
all  of  nearly  uniform  size,  but  still  unfortunately  much  broken 
and  fragmentary.  The  supraglenoid  foramen  pierces  the  supra- 
glenoid  fossa,  not  opening  on  the  dorsal  side  of  the  scapula,  as  I 
have  observed  it  in  all  other  theromorphous  forms  from  the  Ameri- 
can Permian.  There  is  no  process  on  the  upper  margin  of  the 
posterior  coracoid,  above  the  glenoid  cavity,  so  conspicuous  in 
Dimetrodon. 

Humerus  (Plate  XXXV,  Fig.  5).— The  humerus  differs  from 
that  of  most  species  of  Dimetrodon  in  its  greater  relative  ter- 
minal expansions,  its  shaft  being  less  slender  and  shorter.  The 


84  AMERICAN  PERMIAN  VERTEBRATES 

ectepicondylar  process  is  much  more  prominent  and  transverse 
in  position.  The  concavity  of  the  radial  side  is  much  deeper. 
With  the  humerus  of  D.  incisivus  the  resemblance  is  somewhat 
greater.  It  also  resembles  the  humerus  from  New  Mexico  assigned 
by  Case  to  Dimetrodon  navajoicus,  but  I  feel  assured  the  forms 
are  of  different  genera.  Because  of  its  size  and  general  characters 
the  present  specimen  may  well  belong  with  Sphenacodon,  rather 
than  Ophiacodon. 

Ulna  (Plate  XXXV,  Fig.  9).— The  ulna  is  a  distinctly  less 
slender  bone  than  that  of  Dimetrodon;  its  olecranon  process  is 
not  produced  in  the  specimen  figured,  and  scarcely  so  in  other 
fragmentary  specimens.  The  sigmoid  fossa  is  not  as  deep,  and 
the  shaft  is  broader. 

Radius  (Plate  XXXV,  Figs.  10,  n). — The  radius  also  is  less 
slender  than  in  Dimetrodon.  The  bone  is  moderately  expanded  at 
either  extremity,  with  the  concavities  of  the  sides  nearly  equal. 
The  upper,  articular  end  is  nearly  semicircular  in  outline;  the 
lower  one,  subcrescentric,  with  the  outer  horn  the  thinner. 

POSTERIOR   GIRDLE   AND   EXTREMITY 

Ilium  (Plate  XXXVII,  Figs.  4,  5).— Among  all  the  bones  of  the 
posterior  girdle  and  extremity  there  is  none  so  characte'ristic  as 
the  ilium.  The  present  ilium  differs  materially  from  that  of 
Dimetrodon,  resembling  more  that  of  Theropleura  or  Varanosaurus 
in  its  narrow  posterior  prolongation  and  the  presence  on  the 
inner  side  of  the  strong,  horizontal,  keel-like  projection,  quite  as 
Case  has  figured  it  in  Theropleura.  The  articular  surface  for  the 
ischium  is  much  longer  than  that  for  the  pubis,  and  the  two  meet 
in  nearly  a  right  angle.  Of  the  five  or  six  ilia  in  the  collection, 
the  one  figured  is  the  smallest. 

Ischium. — The  ischia,  of  which  there  are  several  in  the  collection, 
all  incomplete,  agree  quite  with  those  of  Theropleura,  as  figured 
by  Case  (Pelycosauria,  Plate  III,  Fig.  6).  The  ischia  generally 
in  the  Permian  reptiles  are  uncharacteristic. 

Pubis. — The  pubes  seem  to  be  quite  similar  to  those  of  Varano- 
saurus, having  a  strongly  projecting  anterior  plate,  twisted  to  a 
horizontal  position  in  the  articulated  skeleton.  This  bone,  as 


REPTILIA:    VARANOSAURUS  85 

described  in  Varanosaurus,  has  a  like  form  in  both  the  Poliosauridae 
and  Clepsydropidae. 

Femur  (Plate  XXXVII,  Fig.  3).— The  femur  resembles  that  of 
Theropleura  more  closely  than  that  of  Dimetrodon  in  its  relatively 
greater  terminal  expansions  and  especially  in  the  greater  extent 
of  the  digital  fossa,  which  reaches  nearly  a  third  of  the  length  of 
the  bone.  Four  femora  of  the  collection  are  very  nearly  of  the 
size  and  shape  of  the  one  figured;  a  fifth  has  a  materially  stouter 
shaft,  though  differing  in  no  other  way  that  I  can  see. 

Tibia  (Plate  XXXV,  Fig.  6)  and  fibula  (Plate  XXXV, 
Fig.  7). — These  bones  are  not  very  characteristically  different 
from  those  of  either  Theropleura  or  Dimetrodon.  Both  are  con- 
siderably curved  away  from  each  other,  the  outer  border  of  the 
fibula  nearly  straight,  the  inner  deeply  concave. 

There  are  also  four  tibialia  and  four  fibularia  which  scarcely 
differ  from  those  of  Dimetrodon,  save  in  size;  and  numerous  tarsal 
and  carpal  bones  of  different  kinds.  Perhaps  some  of  them  belong 
with  Nothodon. 

As  I  have  said,  the  differences  between  these  bones  and  corre- 
sponding ones  of  Dimetrodon  are  so  striking  that  I  cannot  believe 
that  they  belong  with  Sphenacodon,  which  in  its  skull  characters 
is  scarcely  distinguishable  from  that  genus.  It  is  for  this  reason 
that  I  refer  them  provisionally  to  Ophiacodon,  though,  it  must  be 
confessed,  the  entire  absence  of  long-spined  vertebrae  in  the  collec- 
tion coming  from  this  bone-bed  throws  much  doubt  over  their 
determination,  as  well  as  the  affinities  of  Sphenacodon. 


VARANOSAURUS 

Broili,  Paleontographica,  LI,  71,  1904;   Case,  Pelycosauria,  20,  79,  1908. 

Varanosaurus  bremrostris,  n.  sp.     Plates  I-XIII. 

The  genus  Varanosaurus  was  defined  by  Broili  from  a  con- 
siderable part  of  a  skeleton  found  on  West  Coffee  Creek,  Texas, 
which  he  referred  to  a  new  species,  V.  acutirostris*  The  type 

1  Broili,  op.  cit.,  p.  71,  PI.  X,  Fig.  2;  PI.  XI;  PI.  XII,  Figs.  22-32;  Case,  op.  cit., 
PI.  II. 


86  AMERICAN  PERMIAN  VERTEBRATES 

specimen  of  Broili's  species  consists  of  a  fairly  complete  skull, 
thirty-four  vertebrae  in  a  more  or  less  continuous  series,  including 
the  sacrum  and  basal  caudals,  and  parts  of  the  girdles  and  limbs. 
So  far  as  this  material  goes  Broili's  descriptions  and  figures  apply 
well  to  the  abundant  material  herein  described,  and  there  can  be 
no  doubt  of  their  generic  identity.  Indeed,  it  was  not  until  I  had 
critically  studied  the  skulls  and  compared  them  with  Broili's 
figures  and  descriptions  that  I  was  forced  to  recognize  the  specific 
distinction  of  our  form.  In  his  choice  of  a  generic  name  Dr. 
Broili  was  very  happy,  since  the  general  resemblance  of  the  genus 
to  Varanus  is  very  striking. 

The  material  of  V.  bremrostris  herein  described,  and,  I  trust, 
faithfully  figured,  forms  a  part  of  that  of  the  remarkable  bone- 
bed  described  on  the  preceding  pages  as  the  Cacops  bone-bed, 
situated  about  five  miles  west  of  the  Vernon  road,  near  the  Wichita 
River,  in  Baylor  County,  Texas. 

The  remains  of  Varanosaurus  from  this  bone-bed,  all  of  which 
are  referred  with  assurance  to  the  single  species,  comprised  origi- 
nally not  less  than  twenty-five  skeletons,  of  which  six  or  eight  in 
greater  or  less  perfection  have  been  recovered  from  the  blocks  of 
matrix  in  which  they  were  brought  to  the  museum.  The  develop- 
ment of  these  skeletons  is,  however,  very  tedious,  each  requiring 
about  two  months  of  continuous  work.  For  this  reason  not  much 
has  yet  been  done  with  others  than  the  one  described  and  mounted, 
save  where  it  was  found  necessary  or  desirable  to  complete  or 
corroborate  the  knowledge  furnished  by  the  single  specimen.  Un- 
fortunately, so  far  but  three  skulls  have  been  found  in  the  matrix, 
and  one  of  these  is  a  mere  fragment.  There  still  remains  nearly 
a  half  of  the  material  secured  unexamined,  and  it  is  almost  certain 
that  when  this  shall  have  been  worked  out  other  skulls  will  be 
detected.  But  to  wait  until  this  is  done  would  delay  the  publica- 
tion of  the  work  unduly.  I  can  therefore  promise  within  the  next 
few  years  another  paper  upon  the  skull,  not  only  of  Varanosaurus, 
but  also  of  Casea,  and  I  content  myself  here  with  a  preliminary 
description,  together  with  a  reconstruction  of  the  skull  as  based 
upon  the  material  so  far  worked  out,  material  which  furnishes 
the  more  essential  characters  of  the  reptile,  but  which  still  leaves 


REPTILIA:   VARANOSAURUS  87 

many  details  concerning  the  sutures  especially  which  are  impos- 
sible to  determine  with  anything  like  assurance. 

Skull. — Of  the  three  specimens  of  skull  which  have  so  far  been 
prepared,  one,  that  belonging  with  the  mounted  skeleton,  is  a  frag- 
ment consisting  of  the  right  maxilla  and  the  corresponding  part 
of  the  mandible.  It  is,  however,  of  considerable  interest,  since  the 
teeth  are  in  good  condition.  The  second  specimen,  the  skull  shown 
in  the  photograph  of  the  mounted  skeleton,  lacks  the  end  of  the 
rostrum  in  front  of  the  hind  margin  of  the  nares;  the  posterior 
arch  supporting  the  quadrate  of  the  right  side  is  injured,  and  the 
left  arch  and  quadrate  are  lacking;  the  skull  is  slightly  skewed 


FIG.  25. — Varanosaurus    brevirostris     Williston. 
thirds  natural  size. 


Skull,    from    the    side,    two- 


to  the  right.  The  third  skull,  the  best  of  the  three,  has  the  region 
in  front  of  the  middle  of  the  orbits  very  nearly  perfect,  and  but 
slightly  skewed;  the  left  orbit  is  complete,  but  the  left  quadrate 
is  lacking,  as  also  the  posterior  orbital  bar  of  the  right  side.  The 
right  posterior  arch  supporting  the  quadrate  is  pressed  downward 
and  somewhat  outward,  narrowing  the  temporal  vacuity  somewhat; 
but  this  bar  is  shown  in  apparently  normal  form  in  the  other 
skull.  The  mandibles  of  both  specimens  have  been  crowded  up- 
ward and  inward,  obscuring  the  palate  so  much  that  no  attempt 
has  been  made  to  free  this  region  from  its  incrusting  matrix. 
Fortunately  in  both  skulls,  on  both  sides,  the  lower  temporal 
region  is  nearly  or  quite  uninjured,  leaving  no  doubt  as  to  the 


88 


AMERICAN  PERMIAN  VERTEBRATES 


structure  here.  The  drawings  here  given  are  in  part  a  composite 
of  the  three  specimens,  all  of  which  quite  agree  in  size.  For 
comparison  I  also  give  an  outline  sketch  figure  of  the  skull  of 
Varanosaurus  acutirostris,  copied  from  the  original  by  Broili. 


FIG.  26. — Varanosaurus  brevirostris 
Williston.  Skull,  from  above,  two-thirds 
natural  size. 


FIG.  27. — Varanosaurus  acutrirostris 
Broili.  Skull,  from  above,  two-thirds 
natural  size.  After  Broili. 


The  upper  surface  of  the  skull  between  and  immediately  in 
front  of  the  orbits  is  gently  concave.  At  the  upper  anterior  angle 
of  the  orbit  there  is  an  elevated  protuberance,  which  extends 


REPTILIA:    VARANOSAURUS  89 

forward  as  a  ridge  on  the  sides  of  the  face  to  about  midway  between 
the  orbit  and  the  hind  border  of  the  nares ;  and  another  pronounced 
ridge  extends  downward  and  forward  nearly  to  the  alveolar  margin 
opposite  the  large  mandibular  tooth.  The  profile  of  the  face  in 
front  is  gently  convex  to  the  extreme  front  end,  which  overhangs 
slightly  the  alveolar  margin.  On  either  side  the  face  is  somewhat 
pinched  in,  forming  a  somewhat  shallowly  concave  fossa  on  each 
side.  The  nares  are  small,  situated  near  the  extremity  of  the 
rostrum,  arid  they  are  directed  laterally.  The  orbits  are  nearly 
circular  in  outline,  with  a  heavy,  thickened  anterior  border,  more 
pronounced  above  back  of  the  antorbital  elevation.  Within  the 
orbit  is  seen  a  descending  plate  on  each  side,  reaching  apparently 
nearly  or  quite  to  the  pterygoid,  from  the  frontal  above,  emarginate 
in  front,  altogether  resembling  the  rhinencephalic  chamber  figured 
by  me  in  Cacops  (Bull.  Geol.  Soc.  Amer.,  XXI,  Plate  VIII).  The 
posterior  bar  of  the  orbits  is  moderately  stout,  bounding  the  large 
temporal  vacuity  in  front.  Posteriorly  on  each  side  above  a  thick- 
ened sinuous  bar  extends  backward  and  then  downward  to  the 
extremity  of  the  quadrate;  this  bar  is  not  quite  complete  on  the 
upper  and  inner  sides  behind  in  either  skull.  Between  these 
suspensorial  bars  the  occipital  surface  slopes  downward  from  not  far 
back  of  the  orbits  in  a  broad,  flattened,  or  somewhat  convex  surface 
to  the  upper  border  of  the  foramen  magnum,  with  a  thinned, 
rounded  contour  on  each  side,  as  seen  from  above.  The  occipital 
condyle  projects  moderately  beyond  this  border;  it  is  gently  con- 
vex at  its  end,  somewhat  heart-shaped,  and  has  a  dimpling  in  the 
middle,  the  remains  of  the  notochordal  canal.  The  odontoid,  in 
articulation  with  the  skull  in  both  skulls,  is  shown  in  the  figure  from 
above. 

The  most  remarkable  character  in  the  skull  of  Varanosaunis 
is  the  absence  of  the  lower  temporal  arcade;  a  character  wherein 
the  genus  differs  from  all  other  known  genera  of  reptiles,  save  the 
Squamata.  The  jugal  bone  ends  as  a  slender,  pointed  process, 
a  short  distance  beyond  the  pointed  extremity  of  the  maxilla. 
Perhaps  in  life  there  was  a  ligamentous  connection  between  this 
extremity  of  the  jugal  and  the  quadrate,  but  there  is  no  roughening 
in  these  specimens  indicative  of  such.  Unfortunately  the  precise 


QO  AMERICAN  PERMIAN  VERTEBRATES 

curvature  of  the  upper  posterior  border  of  the  vacuity  cannot  be 
determined.  In  one  specimen  the  arch  is  very  complete  and  undis- 
torted,  but  it  has  been  partly  broken  away  from  the  side  of  the 
skull  above  and  pressed  outward  and  downward;  in  the  other  the 
outline  seems  to  be  quite  normal,  as  I  have  figured  it.  The  vacuity 
is  very  large,  comprising  nearly  the  whole  of  the  side  of  the  skull 
back  of  the  orbits,  with  thin  margins  above  and  on  the  sides,  open 
for  the  greater  part  of  the  distance  below  between  the  teeth  and 
the  quadrate.  In  this  space  the  quadrate  is  shown  in  both  speci- 
mens as  a  broad,  oblique  plate  extending  inward  and  forward, 
nearly  as  far  as  the  posterior  border  of  the  orbit,  articulating  above 
and  exteriorly  with  the  suspensorial  arch,  doubtless  chiefly  the 
squamosal;  below  and  within  with  the  pterygoid.  Its  articular 
surface  below  is  broad  from  side  to  side.  The  squamosal  doubtless 
reaches  nearly  to  the  articular  end  on  the  outer  side.  There  are 
no  indications  of  sutures  here,  as  generally  elsewhere.  Doubtless 
also  the  quadratojugal  is  entirely  wanting. 

The  palatal  region,  as  already  stated,  cannot  be  laid  bare  from 
below,  because  of  the  mandibles,  but  in  one  specimen  the  ptery- 
goid and  palatines  have  been  laid  bare  from  above  back  of  the  front 
margin  of  the  orbit.  They  meet  or  nearly  meet  in  the  middle  line 
below  the  orbits  and  seem  to  be  in  contact  with  the  descending 
plates  from  the  f rentals;  they  are  in  close  contact  on  the  sides 
with  the  maxillae  as  far  back  as  their  extremity;  back  of  these  is 
the  free  transpalatine  process,  which  reaches  as  far  as  the  extremity 
of  the  jugal  and  a  considerable  distance  back  of  the  orbit. 

The  teeth  are  slender  and  conical,  extending  back  to  the  extrem- 
ity of  the  maxillae  and  for  some  distance  back  of  the  orbits  and 
below  the  temporal  vacuity.  I  count  not  more  than  thirty  in  each 
maxilla,  with  not  more  than  three  in  each  premaxilla.  Opposite 
the  pronounced  antorbital  ridge,  directed  downward  and  forward 
from  the  antorbital  elevation  and  at  about  two-fifths  the  distance 
between  the  orbit  and  the  hind  margin  of  the  nares,  there  is  a  stout 
maxillary  tooth  on  each  side,  nearly  twice  the  length  of  those  in 
front  and  behind.  The  other  maxillary  teeth  are  of  nearly  equal 
size,  perhaps  somewhat  smaller  in  front.  The  most  anterior  one 
of  the  premaxillae  is  a  little  elongated.  The  mandibles  are  so 


REPTILIA:    VARANOSAURUS  91 

closely  united  with  the  maxillae  that  the  character  and  number 
of  the  teeth  cannot  be  made  out. 

Varanosaurus  acutirostris  Broili,  so  far  as  the  skull  and  skeletal 
characters  are  determinable  from  the  figures  and  descriptions  by 
the  author  in  the  incomplete  condition  of  the  type  specimen,  agrees 
well  with  the  present  species,  save  in  the  skull  proportions  and  the 
teeth.  As  seen  in  the  figure,  the  skull  of  V.  acutirostris  is 
more  elongated  and  slender,  the  length  in  front  of  the  orbits  being 
equal  to  three  times  the  diameter  of  the  orbits,  the  orbits  situated 
back  of  the  middle  of  the  skull.  In  the  present  species  the  length 
in  front  is  scarcely  more  than  twice  the  diameter  of  the  orbit, 
and  the  orbits  are  in  front  of  the  middle  of  the  skull.  Furthermore, 
there  is  no  large  tooth  in  the  position  of  the  mandibular  tooth  of  the 
present  species,  the  enlarged  tooth  of  V.  acutirostris  being  much 
farther  forward.  Furthermore,  and  more  important,  Broili  gives 
fifty-four  as  the  whole  number  of  teeth  in  the  upper  jaws  of  this 
species,  while  there  are  not  more  than  thirty-four  in  V.  brevirostris. 
Notwithstanding  these  differences,  so  great  is  the  general  resem- 
blance between  the  two  that  I  have  been  reluctant  to  admit  the  dis- 
tinction of  our  species.  But  such  differences  cannot  possibly  be 
due  to  either  age  or  individual  variation.  I  have  therefore  given 
to  the  present  species  the  name  Varanosaurus  brevirostris. 

In  the  phylogeny  of  the  reptilia  we  have  assumed  a  high  degree 
of  importance  for  the  different  structural  variations  of  the  temporal 
region;  and,  in  general,  I  believe  that  this  assumption  is  justified. 
We  recognize  at  least  three  and  perhaps  four  chief  types  of  reptiles, 
four  chief  phyla  perhaps,  as  based  upon  the  structure  of  this  region: 
The  cotylosaurian  or  stegocrotaphic  type,  in  which  the  temporal 
region  is  wholly  arched  over;  the  double-arched  or  saurocrotaphic 
type,  as  I  have  called  it,  in  which  there  are  two  temporal  vacuities, 
the  upper  one  bounded  below  by  the  union  of  the  squamosal  and 
postorbital,  the  lower  by  the  jugal  and  quadrato jugal ;  and  the 
single-arched  or  therocrotaphic  type,  in  which  the  single  vacuity 
is  bounded  below  by  the  jugal  and  quadrato  jugal;  and  perhaps 
a  fourth  type  in  which  the  upper  arch  and  vacuity  alone  are  present, 
bounded  by  the  squamosal  and  postorbital  below.  But  I  do  not 
feel  so  certain  as  to  the  distinction  between  these  two  latter  types. 


92  AMERICAN  PERMIAN  VERTEBRATES 

Certainly  in  the  Pelycosauria,  and  perhaps  all  the  Theromorpha, 
the  quadra  to  jugal  does  not  enter  into  the  boundary  of  the  lower 
vacuity  and  the  bone  is  often,  perhaps  usually,  absent.  The 
distinction,  then,  must  be  made  exclusively  on  the  union  of  the 
postorbital  with  the  squamosal  below  for  the  upper  vacuity,  their 
separation  for  the  lower.  But  this  distinction  is  a  not  very  con- 
spicuous one;  in  the  plesiosaurs,  for  instance,  the  postorbital 
unites  with  the  squamosal  only  in  a  slight  point  of  contact;  separate 
them  an  inch  and  the  vacuity  would  become  the  lower  one  as  in  the 
Theromorpha,  since  there  is  doubtless  no  quadra  to  jugal  in  the 
Sauropterygia.  On  the  other  hand,  Broom  figures  the  squamosal 
of  Tapinocephalus  as  broadly  meeting  the  postorbital  (Geological 
Magazine,  VI,  543),  even  more  broadly  than  in  the  plesiosaurs, 
and  yet  the  opening  is  assumed  to  be  the  lower  one !  I  confess  that 
to  me  the  distinction  between  the  upper  and  lower  vacuities  seems 
to  be  one  without  a  difference;  nor  can  I  see  any  evidence,  in  the 
temporal  vacuities,  of  phyletic  distinctions  between  the  various 
single-arched  types.  Perhaps  I  am  dull,  but  I  am  inclined  to 
believe  that  all  single-arched  reptiles  have  arisen  from  a  single 
type. 

It  has  been  assumed  that  the  squamate  temporal  arch  has  arisen 
from  a  double-arched  form  by  the  loss  of  the  lower  arcade  and  the 
development  of  streptostyly.  But  I  believe  that  we  are  now 
convinced  that  the  Squamata  are  of  quite  as  primitive  a  descent 
as  is  the  rhynchocephalian  type,  as  urged  by  Huene  and  myself. 
In  Varanosaurus  we  have,  in  addition  to  the  many  marked  skeletal 
resemblances,  presumably  homoplastic,  the  loss  of  the  lower  arcade. 
While  it  is  improbable  that  such  a  type  originally  gave  origin  to  the 
Squamata  by  the  development  of  an  upper  vacuity  and  the  evolu- 
tion of  streptostyly,  yet  it  is  an  interesting  fact  that  just  such 
changes  are  all  that  are  necessary  to  convert  Varanosaurus  from  a 
theromorph  into  a  squamate,  aside  from  the  rib  attachments,  so 
far  as  we  yet  know. 

Vertebrae  and  ribs  (Plates  I,  II,  III). — The  vertebral  column,  as 
shown  in  the  mounted  skeleton,  was  found  in  perfect  articulation 
from  the  skull  to  the  forty-seventh  caudal  vertebra.  A  few  of  the 
spines  of  the  anterior  vertebrae  protruding  from  the  surface  of  the 


REPTILIA  :   VARANOSAURUS  93 

block  of  the  matrix  as  collected  had  been  broken  off  and  lost,  some 
six  or  seven  in  all;  four  of  these  have  been  replaced  in  the  skeleton 
by  corresponding  vertebrae  of  another  skeleton,  but  the  figures 
given  are  those  of  the  single  specimen.  This  series  is  composed 
of  twenty-seven  presacral,  two  sacral,  and  forty-seven  caudal 
vertebrae,  to  which  may  be  added  a  few,  perhaps  half  a  dozen, 
minute  terminal  ones  that  were  lost.  Of  the  atlas,  only  the  odon- 
toid could  be  recovered  from  the  matrix;  the  arches  were  so  im- 
pressed upon  a  fragment  of  the  occipital  region  of  the  skull  that 
they  could  not  be  separated.  The  figure  in  the  plate,  together 
with  others  of  a  closely  allied  form  from  the  Craddock  bone-bed 
(Plate  VII),  will  show  the  shape  of  this  bone  sufficiently  well  I 
hope.  Its  posterior  surface  is  deeply  concave,  in  apposition  with 
the  centrum  of  the  axis;  the  perforation  continues  through  the 
bone  with  a  small  aperture  in  front,  which  coincided  with  a  small 
pit  in  the  end  of  the  occipital  condyle.  The  upper  surface  of  the 
odontoid  is  slightly  concave  for  the  floor  of  the  neural  canal.  The 
bone  in  the  middle  reaches  the  ventral  side,  separating  the  atlantal 
and  axial  intercentra.  The  surface  for  the  atlantal  intercentrum 
is  a  little  larger  than  that  for  the  axial.  On  either  side  in  front 
there  is  a  somewhat  oblique  surface  for  the  articulation  of  the  atlan- 
tal arch.  In  the  plate  I  give  the  outlines  of  the  basioccipital  and 
atlantal  intercentrum  found  attached  in  another  skeleton  of  the  same 
species.  The  atlantal  intercentrum,  it  is  seen,  is  relatively  small, 
not  much  larger  than  the  axial,  with  only  small  attachment  for  the 
arch,  which  must  have  rested  for  the  most  part,  if  not  entirely, 
upon  the  odontoid  or  pleurocentra,  as  in  Poecilospondylus  Case. 
It  is  very  evident  that  we  have  to  do  here,  as  in  Dimetrodon,  with 
a  primitive  condition  of  the  atlas,  a  condition  in  which  it  differs 
very  slightly  from  the  ordinary  vertebra,  one  in  which  the  atlantal 
arch  is  supported  almost  wholly  by  the  pleurocentra,  articulating 
not  only  by  the  usual  zygopophysial  way  with  the  axis,  but  appar- 
ently with  the  exoccipitals  as  well,  as  shown  in  Dimetrodon,  by  an 
articular  surface  on  either  side  of  the  foramen  magnum.  These 
may  be  for  an  unrecognized  proatlas.  Several  very  perfect  atlantal 
arches  are  preserved  among  the  Craddock  bone-bed  material, 
which  will  be  figured  and  discussed  elsewhere. 


94  AMERICAN  PERMIAN  VERTEBRATES 

The  axis  has  a  rather  long,  stout,  not  very  high  spine;  it  has 
feeble  articulations  in  front  for  the  atlantal  arches.  It  has  a  rather 
short,  but  stout  diapophysis  on  each  side,  directed  downward  and 
somewhat  posteriorly,  for  the  axial  rib,  which,  however,  has  not 
yet  been  recovered  in  natural  relations. 

Of  the  succeeding  twenty-five  presacral  vertebrae,  the  spines 
are  nearly  uniform  in  character,  save  of  the  posterior  five  or  six. 
They  are  vertical  in  position,  flat  and  thin,  a  little  broader  above, 
with  a  very  thin  front  edge  and  a  somewhat  thicker  posterior  one, 
and  are  equal  in  height  to  about  three  times  the  vertical  diameter 
of  the  centra;  the  upper  end  is  rather  squarely  truncate.  With  the 
sixth  presacral  the  spines  begin  to  incline  a  little  forward,  becoming 
successively  more  oblique  and  more  pointed  and  rounded  at  the 
end.  The  highest  spines  are  those  between  the  tenth  and  fifteenth 
presacrals,  but  the  increased  height  is  not  great.  The  zygapophyses 
are  nowhere  very  broad  or  stout,  their  articular  surfaces  looking 
uniformly  obliquely  outward  and  inward.  The  shapes  and  posi- 
tions of  the  diapophyses  are  shown  sufficiently  well  by  the  figures, 
and  need  but  a  brief  description.  As  seen  in  Plate  II,  Fig.  i,  they 
are  the  largest,  stoutest,  and  longest  on  the  anterior  vertebrae, 
about  opposite  the  upper  end  of  the  scapulae,  from  the  twentieth 
to  the  twenty-fourth  presacral,  quite  in  the  corresponding  part  of 
the  column  in  the  lizards.  Anteriorly  they  are  directed  more 
downward  and  backward;  on  the  twenty-first  and  twenty-second 
downward;  on  all  the  following  directly  outward.  From  the 
twenty-first  backward,  they  decrease  gradually  in  length  and  in 
stoutness.  The  last  five  diapophyses — that  is,  those  of  the  first 
five  presacrals — have  short  ribs  co-ossified  with  them,  as  in  other 
Permian  reptiles  as  a  rule,  the  head  descending  a  little  on  the  body, 
leaving  a  small  foramen  between  it  and  the  tubercle. 

The  centra,  unlike  those  of  Casea,  are  of  nearly  uniform  length 
throughout,  somewhat  shorter  and  higher  posteriorly;  anteriorly 
the  " pinching  in"  of  the  sides  produces  a  rather  sharp  keel  below, 
but  posteriorly  this  keel  is  broader  and  more  rounded.  Intercentra 
are  in  place,  as  shown  in  the  figures,  between  various  ones  of  the 
vertebrae;  they  are  of  moderately  large  size,  larger  than  in  Casea. 
Between  the  third  and  fourth,  and  the  fourth  and  fifth,  and  less 


REPTILIA:   VARANOSAURUS  95 

so  between  the  fifth  and  sixth,  the  intercentral  spaces  are  large, 
the  cartilaginous  surface  extending  back  a  considerable  distance 
on  the  underside  of  the  succeeding  centra.  J^vidently  there  was 
considerable  mobility  between  the  vertebrae  here. 

Ribs  (Plate  I). — Most  of  the  ribs  of  this  skeleton  were  found  in 
close  articulation  with  the  vertebrae,  but  they  were  so  slender  and 
frail  and  so  firmly  cemented  together  by  the  matrix  as  they  lay 
partly  folded  over  each  other  that  only  a  few  could  be  extricated  in 
good  shape.  In  the  figures  I  give  illustrations  of  some  of  the  best 
of  these,  those  found  associated  with  the  fifteenth  to  the  eighteenth 
presacral  vertebrae.  As  is  seen  in  the  figures,  they  are  very  dis- 
tinctly double-headed,  the  head  articulating  as  usual  in  the  inter- 
central  space,  the  tubercle  to  the  end  of  the  diapophysis.  They 
are  very  gently  curved  in  nearly  one  plane,  very  unlike  the  stout 
ribs  of  Casea,  and  they  are  relatively  slender.  Evidently,  as  in 
lizards,  they  had  a  long,  cartilaginous  continuation.  On  the  first 
three  or  four  presacrals  they  are  little  more  than  tubercles,  gradually 
becoming  longer,  and  becoming  free,  or  nearly  so,  on  the  sixth. 

Ventral  ribs. — It  is  very  evident  that  the  whole  underside  of  the 
abdominal  region  of  Varanosaurus  was  covered  by  slender  and 
numerous  ventral  ribs,  lying  close  together  and  doubtless  meeting 
in  a  V-shaped  angle  in  the  median  line.  Only  isolated  patches  of 
these  ribs  have  been  recovered.  In  a  single  piece  fifty  millimeters 
in  length  and  twenty-five  millimeters  in  width  I  count  fourteen 
ribs,  continuous  and  parallel.  Freed  from  their  incrusting  matrix 
they  are  little  more  than  one  millimeter  in  diameter,  and  I  doubt 
not  that  some  of  them  reached  a  length  of  four  or  five  inches;  the 
longest  I  have  observed  are  about  three  inches. 

The  sacrum  (Plate  III;  Plate  IV,  Fig.  8;  Plate  VI,  Fig.  7;  Plate 
XI). — This  is  composed  of  two  vertebrae,  which  through  their  mas- 
sive ribs  have  a  firm  union  with  the  pelvis.  The  spines  are  nearly 
vertical,  or  convergent,  somewhat  rounded,  and  pointed  at  their 
extremity,  narrower  and  rather  stouter  than  the  preceding  ones. 
The  zygapophyses  are  not  very  heavy;  the  centra  are  rather  sharply 
carinate  below,  and  an  intercentrum  is  present  between  the  two. 
The  anterior  ribs,  much  the  larger  of  the  two  pairs,  arise  from  the 
anterior  two-thirds  of  the  centrum  and  the  corresponding  part  of 


96  AMERICAN  PERMIAN  VERTEBRATES 

the  arch,  with  both  of  which  they  are  closely  fused,  with  only  indi- 
cations of  the  distinguishing  sutural  attachments.  A  few  milli- 
meters from  the  origin  the  rib  contracts  into  a  stout  trihedral 
or  prismatic  shape,  and  then  immediately  expands  into  a  wide 
extremity  with  a  periphery  of  about  three-fifths  of  a  circle  whose 
chord  is  above,  hollowed  into  a  deep  cavity  which  looks  nearly 
upward  in  the  articulated  skeleton.  The  rib  is  so  directed  that  the 
plane  of  the  anterior  end  of  the  centrum  passes  through  the  middle 
of  the  cavity  and  the  posterior  fifth  of  the  acetabulum.  The  second 
pair  of  ribs  are  more  slender  and  are  directed  more  obliquely  for- 
ward. The  base,  attached  as  in  the  first  pair,  is  less  robust,  the 
shaft  more  slender,  and  the  simple  terminal  expansion  curves  some- 
what downward  to  be  attached  to  the  posterior  expansion  of  the 
ilium,  wholly  back  of  the  acetabulum;  the  extremity  is  suturally 
attached  at  the  anterior  corner  with  the  posterior  part  of  the  end 
of  the  first  rib. 

Caudal  vertebrae  (Plate  III). — Forty-seven  caudal  vertebrae 
were  found  associated  in  the  mounted  specimen  in  an  uninterrupted 
and  nearly  straight  series,  and  they  have  been  mounted  practically 
without  disturbance  of  the  matrical  attachments.  Perhaps  a 
half-dozen  of  the  minute  terminal  ones  were  missing.  The  centra 
throughout  are  nearly  uniform  in  length.  Chevrons  were  found 
associated  with  many,  if  not  the  most,  of  the  vertebrae,  but  the 
delicate  structure  of  many  of  the  smaller  ones  rendered  it  inexpedi- 
ent to  attempt  their  recovery;  some  of  those  posteriorly  were 
appressed  against  the  centra  and  have  been  left  in  that  position. 
Figures  are  given  in  the  plate  of  those  chevrons  recovered  in  this 
specimen,  and  in  the  photograph  of  the  skeleton  others  are  seen 
that  have  been  modeled  to  correspond  with  isolated  or  attached 
ones. 

The  first  four  or  five  centra  have  a  rather  sharp  keel  below, 
becoming  a  little  more  obtuse  posteriorly.  By  the  sixteenth  or 
seventeenth  the  centra  have  lost  nearly  all  of  the  lateral  concavity 
or  depression,  and  thenceforth  a  cross-section  through  the  middle 
forms  a  rather  regular  semioval  figure.  Between  the  second  sacral 
and  the  first  caudal  there  is  space  for  a  small  intercentrum.  Below 
the  first  and  second  caudals  the  space  is  moderately  large,  yet 


REPTILIA:   VARANOSAURUS  97 

altogether  too  small  for  the  attachment  of  a  chevron.  That 
between  the  second  and  third  is  larger.  At  the  end  of  the  third 
there  is  a  large  facet  for  the  attachment  of  a  chevron,  whose  union 
was  almost  wholly  with  the  third.  Lying  near  these  were  several 
large  chevrons  with  an  obtuse  extremity,  and  a  shorter  one  with 
a  more  pointed  extremity.  I  have  figured  this  short  one  as  attached 
to  the  end  of  the  second  centrum,  with  the  three  large  ones  following 
it;  on  further  reflection  I  very  much  doubt  whether  there  was  a 
chevron  attached  here — in  other  words,  there  were  doubtless  two 
pygal  vertebrae  as  in  Casea  and  other  forms;  otherwise  the  chevrons 
would  have  projected  into  the  pelvic  cavity,  as  they  have  been  so 
often  figured  in  Diplodocus. 

The  spines  of  the  anterior  caudal  vertebrae  are  nearly  vertical; 
at  the  sixth  the  spine  is  shorter,  more  pointed,  and  inclined  a  little 
forward.  With  the  twelfth — that  is,  the  vertebra  bearing  the  last 
transverse  process  or  co-ossified  rib — the  spines  have  become  mere 
tubercles,  and  thence  onward  they  do  not  change  much,  becoming 
entirely  lost  before  the  end  of  the  tail. 

The  ribs  of  the  first  four  caudal  vertebrae  are  attached  by  a 
short,  stout  proximal  end  to  both  arch  and  centrum.  On  the 
underside  near  the  body  a  pit  or  cavity  seems  to  indicate  the  natural 
division  into  head  and  tubercle,  the  capitular  portion  descending 
lower  on  the  front  margin  of  the  centrum.  These  four  ribs  decrease 
in  size ;  they  are  all  pointed,  with  the  point  curved  directly  backward 
parallel  with  the  axis  of  the  tail,  and  they  are  horizontal.  The 
much  smaller  fifth  rib  is  directed  outward  horizontally  and  is  also 
pointed  at  its  extremity.  The  following  ribs  or  processes  decrease 
in  length,  terminating  as  a  small  tubercle  on  the  twelfth;  they 
ascend  on  the  centrum  as  far  back  as  the  eighth.  Thence  to 
the  last  one  preserved  in  the  connected  series,  the  forty-seventh, 
the  centra  are  similar,  becoming  gradually  more  slender,  the 
spines  finally  becoming  obsolete;  their  chevrons  are  slender  to 
the  extremity. 

Pectoral  girdle  and  extremity  (Plates  IV-VIII) .— The  ossified 
pectoral  girdle  is  composed  of  the  scapula  and  so-called  procora- 
coid,  clavicles,  and  interclavicle.  The  posterior  coracoid,  the 
so-called  true  coracoid,  is  unossified  in  all  the  numerous  specimens 


98  AMERICAN  PERMIAN  VERTEBRATES 

examined;  and  there  is  no  trace  of  cleithrum  in  any  of  the  speci- 
mens examined. 

The  upper  end  of  the  scapula  is  moderately  expanded  in  nearly 
a  plane,  its  upper  margin  very  slightly  convex,  and  squarely 
truncated,  as  though  for  a  cartilaginous  suprascapula ;  this  border 
is  about  three  millimeters  in  thickness.  The  posterior  margin 
is  thickened  and  rounded,  and  nearly  straight  for  fully  one-half 
the  length  of  the  conjoined  bone.  The  anterior  border  is  thickened 
moderately  on  the  upper  fourth,  thinned  and  irregular  in  outline 
for  the  remainder  of  its  border.  The  inner  surface  above  is  gentl  y 
convex  antero-posteriorly,  convex  on  the  corresponding  outer 
surface.  Below,  the  posterior  border  turns  a  little  backward 
and  outward  to  end  in  the  preglenoid  tuberosity.  On  the  inner 
surface  a  thickening  begins  below  the  middle  posteriorly,  turning 
backward  in  a  broad  sweep  to  terminate  in  the  cartilaginous 
border  for  the  coracoid  or  metacoracoid.  Between  these  two 
borders  the  surface  for  the  most  part  is  convex,  and  has  no  fossa  or 
foramen  as  in  the  other  reptiles  and  the  amphibians.  The  upper 
part  of  the  glenoid  fossa  is  shallow.  At  some  distance  above  the 
preglenoid  tuberosity  and  back  of  the  middle  of  the  outer  surface 
there  is  a  small  foramen  piercing  the  bone ;  this  is  the  usual  supra- 
glenoid  foramen,  as  I  have  called  it,  but  situated  unusually  far 
forward  and  in  front  of  the  border;  its  position  in  Dimetrodon  is 
very  near  to  this  border,  while  in  scapulae  which  I  have  referred 
to  Ophiacodon  (see  anted)  this  foramen  pierces  the  supraglenoid 
fossa,  as  in  the  Cotylosauria  and  amphibians.  The  scapula-coracoid 
suture  runs  almost  straight  from  a  little  above  the  middle  of  the 
coracoid  border,  through  the  middle  of  the  preglenoid  tuberosity 
or  facet  to  the  angle  immediately  above  the  anterior  emargination 
of  the  so-called  procoracoid.  The  suture  is  clearly  indicated  in 
various  specimens,  and  in  one  the  two  bones  are  separated.  The 
lower  part  of  the  scapula  turns  inward,  so  that  the  coracoid  as  a 
whole  is  nearly  horizontal.  This  latter  bone  is  much  wider  behind 
and  is  thin  throughout  the  most  of  its  extent,  its  inner  border 
lying  by  the  side  of  the  interclavicle,  thinned  throughout  most  of 
its  extent  and  for  the  most  part  nearly  straight;  the  front  border 
is  also  thin,  with  a  subangular  protuberance  and  a  deep  angular 


KEPT  I  LI  A  :    VARANOSAURUS  99 

emargination  above  it,  a  coracoid  fenestra,  between  the  anterior 
angle  of  the  bone  and  the  angle  into  which  runs  the  coraco-scapular 
suture.  This  emargination  reminds  one  forcibly  of  the  similar 
emargination  or  fenestra  in  many  lizards,  and  is,  it  seems  to  me, 
further  proof  of  the  identity  of  the  coracoid  in  these  two  groups  of 
animals.  At  the  posterior  end  the  cartilaginous  border  for  the 
posterior  coracoid  bone  is  thickened  and  rather  broad ;  it  is  formed 
almost  equally  by  the  scapula  and  the  anterior  coracoid  bone; 
that  of  the  scapula  a  little  larger  and  more  protuberant  posteriorly. 
The  thickened  preglenoid  tuberosity  juts  outward  and  backward, 
and  includes  between  it  and  the  glenoid  fossa  a  little  in  front  a 
rather  large  and  deep  fossa,  bounded  behind  by  a  rather  promi- 
nent margin  formed  by  the  two  bones  nearly  opposite  the  preglenoid 
tuberosity  of  the  outer  side;  in  front  of  this  margin  and  in  the 
narrow  fossa  formed  by  it,  the  subscapular  fossa,  the  supracoracoid 
foramen  opens  as  usual. 

The  absence  of  a  posterior  coracoid  bone  in  this  genus,  as  in 
Seymouria  described  in  the  preceding  pages,  is  remarkable.  On 
both  sides  of  the  pectoral  girdle  in  this  skeleton  the  humeri  lay 
quite  in  natural  position,  indicating  its  undisturbed  condition,  but 
separate  ossifications  of  the  posterior  coracoids  were  not  preserved. 
It  was  not,  however,  till  many  other  girdles  of  Varanosaurus  had 
been  observed  with  the  scapula  quite  like  the  one  figured  and  no 
remains  of  separate  bones  in  the  place  of  the  posterior  coracoids 
that  I  became  fully  assured  of  their  entire  absence  in  this  genus; 
that  the  non-occurrence  was  due  neither  to  displacement  of  separate 
ossifications  nor  to  juvenility.  As  it  would  be  absurd  to  suppose 
that  all  the  numerous  skeletons  of  Varanosaurus  found  in  this 
remarkable  deposit  were  juvenile  animals  of  one  size  or  very 
nearly  one  size,  it  is  quite  certain  that  Varanosaurus  had  no  ossified 
posterior  coracoid  in  life.  The  whole  pectoral  girdle  of  Varanosau- 
rus thus  has  an  almost  absolute  superficial  identity  with  that  of 
the  lizards.  Under  the  usual  interpretation,  however,  the  large 
ossified  coracoid  of  Varanosaurus,  with  its  close  resemblance  to 
the  coracoid  of  Varanus,  for  instance,  in  its  supracoracoid  foramen 
and  fenestra,  is  the  procoracoid.  In  other  words,  it  is  assumed 
that  the  coracoid  of  Varanosaurus  has  disappeared  gradually  by 


ioo  AMERICAN  PERMIAN  VERTEBRATES 

the  encroachment  upon  it  of  the  posterior  bone,  the  so-called  true 
coracoid,  which  here  in  this  genus  was  so  degenerate  that  it  no 
longer  was  even  ossified.  It  seems  to  me  that  the  utter  absence 
of  any  proof  that  such  has  been  the  course  of  evolution  in  the 
pectoral  girdle  of  reptiles — for  no  intermediate  form  has  ever  been 
discovered,  no  form  in  which  the  posterior  bone  has  even  reached 
as  far  forward  as  the  supracoracoid  foramen — is  sufficient  to  throw 
great  doubt  upon  the  hypothesis,  a  doubt  that  becomes  quite 
conclusive  in  the  proof  afforded  by  the  various  specimens  of  these 
and  other  Permian  reptiles. 

It  is  a  curious  fact  also  that  a  posterior  coracoid  bone  has  never 
been  observed  in  any  temnospondyl,  though  the  sutural  division 
between  the  scapula  and  coracoid  I  have  observed  in  specimens 
referred  to  Aspidosaurus  to  be  quite  as  in  Seymouria. 

Inter  clavicle  (Plate  IV,  Figs,  i,  2). — The  interclavicle  is  shaped, 
almost  ludicrously,  like  a  miner's  shovel,  with  an  expanded  anterior 
end  and  a  long  curved  handle.  The  anterior  end  in  shape  is  quite 
like  that  of  a  playing  card  spade,  thin  on  its  margins,  concave 
above  in  both  directions,  but  more  so  transversely.  The  k 'handle" 
is  more  than  three  times  the  length  of  the  "blade"  and  is  of  nearly 
uniform  width,  somewhat  narrowed  anteriorly  and  pointed  at  the 
end;  its  upper  side  is  nearly  flat,  the  underside  convex  from  side 
to  side.  In  side  view  the  bone  has  a  rather  long  and  deep  con- 
cavity above  to  the  posterior  third,  which  is  gently  convex  above. 
The  concavity  of  the  upper  side  and  convexity  below  are  nearly 
uniform  to  the  extreme  front  end;  and  this  shape  is  doubtless 
normal,  not  the  result  of  pressure,  since  two  observed  specimens 
agree. 

Clavicles  (Plate  IV,  Figs.  3,  4). — The  two  clavicles  in  the  pres- 
ent skeleton,  as  also  others  which  have  been  developed,  were 
almost  perfectly  in  place,  attached  to  the  interclavicle;  and  they 
are  complete  save  for  the  extreme  tip,  which  has  been  lost  in 
preparation.  The  inner  end  was  expanded  from  before  back, 
more  nearly  like  that  of  Dimetrodon,  a  little  thickened  along  the 
anterior  margin,  quite  thin  on  the  posterior  and  inner  sides,  con- 
cave above  to  fit  the  end  of  the  interclavicle,  with  a  flattened  or 
prismatic  shaft,  and  so  curved  that  it  is  pointed  almost  directly 


REPTILIA:    VARANOSAURUS  101 

upward  in  the  articulated  skeleton.  The  upper  end  gradually 
narrows,  its  flattened  face  in  front  and  external.  In  the  articulated 
skeleton  it  lies  against  the  front  margin  of  the  scapula,  scarcely 
overlapping  it.  As  articulated,  the  two  upper  extremities  of  the 
clavicles  are  less  than  two  inches  apart;  the  anterior  border  is 
directed  obliquely  backward,  the  margin  below  projecting  forward 
and  upward.  As  stated,  no  indications  whatever  have  been  dis- 
covered in  any  skeleton  of  a  clei thrum;  it  was  assuredly  absent. 

Humerus  (Plate  VI,  Figs.  1-6). — The  humerus  is  of  the  "old- 
fashioned"  type,  broadly  expanded  at  each  extremity  and  with  a 
slender  shaft  in  the  middle.  The  planes  of  the  two  ends  meet 
each  other  in  an  angle  of  about  seventy  degrees,  that  of  the  proximal 
turned  outward  from  the  horizontal.  The  proximal  articular 
facet  is  elongated,  narrower  at  the  inner  than  at  the  outer  side; 
its  surface  is  moderately  convex,  with  the  chords  of  its  curves 
almost  at  right-angles  to  the  planes  of  the  proximal  end,  indicating 
an  almost  horizontal  position  of  the  end  in  life.  On  the  dorsal 
side  of  this  extremity,  which  is  convex  from  side  to  side,  there  is 
a  considerable  rugosity  near  the  upper  inner  part,  for  muscular 
attachment.  The  ventral  surface  is  flat  or  gently  concave  for  the 
most  part,  and  the  lateral  process  is  turned  forward,  so  that  its 
thickened  extremity  looks  ventrad  and  is  placed  at  about  the  upper 
third  of  the  bone.  The  distal  extremity  is  much  more  expanded 
than  the  proximal.  The  articulations  for  radius  and  ulna  are 
turned  somewhat  ventrad;  the  larger  inner  one,  for  the  radius, 
arises  mostly  from  the  ventral  surface,  that  for  the  ulna  in  large 
part  from  the  dorsal,  on  either  side  of  which,  on  the  dorsal  side, 
there  is  a  rather  deep  groove.  On  the  more  thinly  expanded  inner 
side,  at  about  the  lower  third  of  the  bone,  is  the  large  epicondylar 
foramen,  which  pierces  the  bone  from  above  downward  and  is 
covered  by  a  thin  and  slender  bridge  of  bone.  On  the  outer  side, 
above  the  condyle,  there  is  a  projection  protruding  beyond  the 
inner  margin  of  the  bone,  from  which  it  is  separated  by  a  narrow, 
but  deep  vertical  groove,  a  process  characteristic  of  some,  if  not  all, 
the  zygocrotaphic  reptiles,  but  wanting  often  in  the  Cotylosauria, 
especially  the  Pariotichidae.  The  expanded  and  somewhat  angular 
inner  condvle  has  a  facet  of  considerable  size  for  the  attachment 


T02  AMERICAN  PERMIAN  VERTEBRATES 

of  the  flexor  muscles.  The  outer  condyle  is  less  expanded,  is  more 
thickened,  and  has  considerable  surface  for  the  extensor  muscles. 
The  shaft,  near  the  middle  of  the  bone,  is  much  contracted  and  very 
short,  subrotund  or  prismatic  in  cross-section. 

Radius  (Plate  VII,  Figs.  1-4). — The  radius  is  a  slender  bone, 
about  three-fourths  the  length  of  the  humerus,  with  only  moder- 
ately expanded  extremities.  It  was  found  in  this  specimen  closely 
articulated  with  both  humerus  and  ulna,  as  shown  in  the  figures 
(Figs,  i,  2).  Its  proximal  articular  surface  is  broader  on  the 
dorsal  than  on  the  palmar  side,  shallowly  concave  above  for  the 
capitellum.  The  shaft  is  curved,  with  the  concavity  on  the  ulnar 
side,  the  outer  margin  thinner  for  the  interosseous  membrane. 
The  lower  extremity  is  transversely  oval,  the  end  concave,  the 
dorsal  side  convex,  the  palmar  more  concave. 

Ulna  (Plate  VII,  Figs,  i,  2,  3,  6). — The  ulna  is  a  little  longer  than 
the  radius,  and  is  much  more  expanded  at  its  extremities  than  that 
bone;  the  shaft  at  its  narrowest  place,  the  lower  third,  is  more 
slender.  The  sigmoid  surface  is  concave  and  is  almost  continuous 
with  that  of  the  radius  for  the  capitellum  in  the  articulated  condi- 
tion. The  olecranon  is  produced  but  little,  and  has  also  a  concave 
ligamentous  surface  for  the  attachment  of  the  triceps.  The 
radial  border  is  concave  throughout,  the  inner  border  convex 
for  fully  three-fourths  its  length,  as  far  as  the  most  slender  part 
of  the  shaft.  The  distal  extremity,  narrower  than  that  of  the 
radius,  is  flattened  oval  and  is  concave  in  the  end. 

That  minor  differences  in  the  shapes  of  the  bones  of  the  skeleton 
are  not  necessarily  due  to  specific  differences  is  apparent  in  many 
of  our  specimens.  In  Plate  VIII,  I  have  figured  the  radius  and 
ulna  of  another  skeleton,  in  which  such  differences  are  very 
apparent,  without  corresponding  differences  in  other  parts  of  the 
skeleton;  they  certainly  belong  in  the  same  species. 

Front  foot  (Plate  VIII;  Plate  VII,  Fig.  5).— The  foot,  as  it  is 
figured  in  Plate  VIII,  is  nearly  wholly  that  of  a  single  specimen, 
but  it  has  been  completed  in  part  and  the  position  of  various 
bones  determined  by  the  aid  of  several  other  specimens.  Unfor- 
tunately many  of  the  phalanges  of  the  three  middle  bones  have  not 
yet  been  found  associated,  though  the  most  of  them,  as  outlined, 


REPTILIA:   VARANOSAURUS  103 

have  been  found  in  connection  with  the  carpus,  but  more  or  less 
disturbed  in  their  relations.  The  complete,  or  nearly  complete 
carpus  has  been  found  in  three  specimens,  with  more  or  less  of  the 
metacarpals  and  phalanges  in  anatomical  association  with  them,  so 
that  their  positions  are  positively  assured,  as  also  their  relations 
with  the  forearm.  The  carpus  is  of  the  same  general  structure  as 
that  of  Dimetrodon  (Plate  VII)  save  that  the  outer  centrale  and  fifth 
distale  were  never  ossified.  Although  the  pisiform  in  Dimetrodon 
has  never  been  found  in  place  I  doubt  not  that  it  has  the  same 
articulations  as  in  Varanosaurus,  Casea,  Limnoscelis,  Trispondylus, 
etc.,  articulating  in  the  interval,  as  in  modern  reptiles,  between  the 
ulna  and  ulnare.  In  the  different  carpi  found  with  the  bones  in 
place  there  is  a  small  interval  between  the  radiale  and  the  first 
and  second  carpalia,  doubtless  filled  out  in  life  by  a  small  cartilage 
representing  the  unossified  centrale,  quite  as  in  the  hind  feet.  And 
this  is  also  the  case  with  the  fifth  carpale.  Although  several  carpi 
have  been  examined  with  carpals  and  metacarpals  all  in  place  and 
in  the  positions  shown  in  the  drawing,  there  is  invariably  a  small 
unossified  space  at  the  proximal  end  of  the  fifth  metacarpal.  As  it 
is  altogether  improbable  that  this  carpale  should  have  been  lost  in 
all  these  specimens,  I  am  quite  assured  that  it  was  never  ossified. 
The  fifth  finger  is  more  reduced  than  is  the  fifth  toe,  and  doubtless 
this  explains  the  vestigial  condition  of  the  carpale. 

The  metacarpal  of  the  first  finger  is  very  small,  and  the  finger 
is  very  short.  This  finger,  with  the  bones  articulated,  has  been 
observed  in  two  different  specimens  quite  in  the  position  given  in 
the  figure,  closely  appressed  to  the  second  finger,  and  this  doubtless 
was  its  normal  position  in  life.  The  much-elongated  fourth  meta- 
carpal in  itself  indicates  an  elongated  fourth  finger,  and  the  pha- 
langes preserved,  if  I  have  correctly  placed  them,  substantiate  the 
conclusion.  The  ungual  phalanges  are  quite  like  those  of  the  hind 
foot,  strong  and  well  curved.  In  the  drawing  the  phalanges  not 
found  in  actual  relations  are  shown  by  the  uniform  shading;  and 
two  or  three  of  the  distal  ones  are  conjectural. 

Pelvic  girdle  and  extremity  (Plates  IX-XIII). — The  pelvis  of 
Varanosaurus  is  noteworthy  for  the  small  size  of  the  ilia  and  the  large 
size  of  the  pubes  and  ischia,  suggesting  the  pelvis  of  the  Sauropte- 


104  AMERICAN  PERMIAN  VERTEBRATES 

rygia.  The  ilium  has  a  long,  thin,  and  narrow  process,  directed 
horizontally  backward.  Its  upper  margin  is  thin,  crest-like,  scarcely 
projecting  above  the  sacral  ribs.  The  anterior  superior  border  in 
front  of  the  sacral  rib  is  thickened  and  rounded.  Fully  three-fifths 
of  the  acetabulum  is  formed  by  this  bone.  It  has  a  strong  overhang- 
ing ridge  or  process  directly  above  the  cavity.  On  the  inner  side 
distinct  facets  are  visible  for  the  attachment  of  the  sacral  ribs,  the 
large  one  in  front  and  below,  the  smaller  one  almost  wholly  on  the 
posterior  process  behind  and  above.  The  pubic  and  ischiadic 
borders  meet  in  a  little  more  than  a  right  angle.  A  little  in 
front  of  the  angle  on  the  inner  side  there  is  a  vertical  depression  or 
groove  continuing  upward  the  depression  leading  into  the  obturator 
foramen. 

The  pubes  are  remarkable  for  their  large  size  and  forward 
extension.  They  are  broadly  expanded  in  front  to  the  full  width  of 
the  pelvis,  extending  forward  almost  parallel  with  the  plane  of  the 
vertebral  column  above  them.  The  two  bones  meet  in  a  long, 
nearly  horizontal  suture,  leaving  an  angular  emargination  in  the 
middle  behind  where  they  turn  downward  into  the  true  brim  of  the 
pelvis.  From  side  to  side  above  the  surface  is  convex,  and  the 
surface  below  is  concave  transversely.  The  thickened  lateral 
borders  turn  downward  from  the  pubo-ischiadic  suture  and  inward 
to  the  horizontal  table,  and  then  outwardly  horizontally  and 
forward.  In  the  middle  behind  the  distance  between  the  two  bones 
is  narrowed  to  form  a  U,  turning  deeply  downward  into  the  narrow 
trough  formed  by  the  two  ischia.  The  pubic  foramen  is  a  little 
in  front  of  the  ischiadic  border,  piercing  the  bone  vertically  as  the 
continuation  of  the  shallow  groove  beginning  above  the  ilium. 
The  inferior  orifice  of  the  foramen  is  an  oval  opening  of  considerable 
size  situated  in  the  angle  between  the  descending  flange  and  the 
ace  tabular  margin. 

The  ischia  are  shaped  very  much  like  those  of  the  long-necked 
plesiosaurs,  hatchet-shaped  bones  which  descend  to  meet  each 
other  angularly,  considerably  below  the  plane  of  the  pubic  expan- 
sion, into  which  cavity  the  downward  deflection  of  the  posterior 
borders  of  the  pubes  open.  They  are  massive  bones,  the  ace- 
tabular  border  especially  protuberant  and  heavy.  The  outer 


REPTILIA:    VARANOSAURUS  105 

surface  is  slightly  concave,  with  the  posterior  upper  thickened 
margin  curved  outward.  The  two  bones  meet  in  an  acute  angle, 
forming  a  deep,  narrow  floor  to  the  pelvic  cavity.  Between  the 
pubes  and  ischia  there  is  a  rather  large  diamond-shaped  opening; 
and  this  opening  was  doubtless  pervious  in  life,  that  is,  it  could  not 
have  been  filled  up  by  cartilage,  I  think,  a  distinct  premonition  of  the 
pubo-ischiadic  vacuity  of  the  Chelonia,  if  not  of  all  modern  reptiles. 

The  peculiar  structure  of  the  pubes  in  this  genus  allies  it  with 
the  true  pelycosaurs  much  more  closely  than  with  the  Caseidae. 
In  life  the  animal  rested  in  repose  wholly  upon  the  ischia,  while 
in  the  Cotylosauria  the  support  of  the  body  was  equally  distributed, 
in  some  at  least,  upon  both  the  pubes  and  the  ischia,  in  both  of  which 
the  symphysis  was  far  more  massive  than  in  the  Pelycosauria. 
Just  what  is  the  significance  of  the  much  elongated,  expanded,  and 
platelike  pubes  I  do  not  understand. 

The  femur  (Plate  XII,  Figs.  1-5)  is  moderately  expanded  at 
either  extremity,  rather  slender  in  the  middle.  The  proximal 
end  shows  a  flattened  surface,  broader  on  its  inner  side,  and  curved 
backward  and  narrowed  at  the  outer  side.  The  trochanter,  on 
the  tibial  side,  is  prominent,  continuing  backward  the  inner  sur- 
face of  the  bone;  it  has  a  small  oval  facet  at  its  extremity,  directed 
proximad  and  ventrad.  Between  this  projection  and  the  outer 
and  proximal  sides  there  is  a  broad,  shallow,  digital  fossa,  which 
extends  downward  for  a  distance  of  about  two-fifths  of  the  length 
of  the  bone.  The  trochanteric  elevation  is  continued  for  a  short 
distance  as  a  distinct  adductor  ridge.  The  shaft  at  the  middle 
is  nearly  circular  in  cross-section,  and  the  bone  is  not  much  curved. 
The  inner  border  of  the  bone  is  deeply  concave  throughout;  the 
outer  one  much  less  so.  The  distal  articular  surface  looks,  for  the 
most  part,  inward  at  an  angle  of  about  twenty  degrees,  and  back- 
ward at  about  forty-five.  Of  the  articular  surface  that  part  on  the 
outer  side  for  the  fibula  is  the  broader,  as  in  Dimetrodon,  with  a 
considerable  antero-posterior  extent,  its  outer  margin  concave  in 
outline.  The  tibial  articular  surface  is  large,  subtriangular  in  shape, 
and  fully  as  wide  as  the  fibular  surface  antero-posteriorly.  The 
intercondylar  groove  in  front  is  deep,  that  behind  is  shallow;  the 
width  of  the  articulating  surface  connecting  the  fibular  with  the 


io6  AMERICAN  PERMIAN  VERTEBRATES 

tibial  is  about  one-third  that  of  either  side.  The  popliteal  surface 
is  shallowly  concave,  occupying  the  lower  fourth  of  the  bone. 

The  tibia  (Plate  XII,  Figs.  6-n)  is  a  little  more  than  three-fifths 
the  length  of  the  femur,  and  has  a  much-dilated  proximal  extremity, 
a  slender,  curved,  subtrihedral  shaft,  and  a  moderately  expanded 
lower  extremity.  The  distal  end  is  curved  backward  so  that  the 
truncated  distal  extremity  is  at  an  angle  of  nearly  forty-five  degrees 
with  the  long  axis  of  the  bone.  The  greater  diameter  of  the 
proximal  articular  surface  is  nearly  transverse  in  position  in  the 
articulated  skeleton.  The  cnemial  elevation  in  front  is  not  very 
broad  or  high,  the  surface  on  the  outer  side  of  it  partly  underlying 
the  fibula  in  articulation;  that  on  the  inner  side  is  convex.  The 
distal  extremity  is  subangular  on  the  inner  anterior  part ;  the  other 
sides  more  rounded. 

The  fibula  (Plate  XIII,  Figs,  2,  3),  hitherto  almost  unknown 
among  the  Texas  reptiles,  is  a  very  slender  bone,  and  is  distinctly 
longer  than  the  tibia,  the  planes  of  its  two  extremities  slightly  twisted 
on  the  longitudinal  axis  at  an  angle  of  ten  or  fifteen  degrees.  The 
proximal  end  is  convex  on  its  outer  dorsal  side,  gently  concave  on 
the  tibial,  the  proximal  articular  surface  long  and  narrow,  oblique 
both  inwardly  and  anteriorly.  The  distal  extremity,  much  the 
broader,  is  also  convex  on  the  dorsal,  concave  on  the  ventral 
side,  with  a  round  distal  outline,  extended  higher  up  on  the  more 
expanded  inner  side.  The  articular  surface,  long  and  narrow  with 
a  slight  sigmoid  curve,  is  directed  somewhat  obliquely  forward.  The 
slender  shaft  is  nearly  straight  in  its  middle  part,  or  slightly 
curved  in  outline. 

Foot  (Plate  XIII,  Fig.  i;  Plate  IV,  Figs.  6,  7).— The  astrag- 
alus, or  tibiale  plus  intermedium,  is  subquadrangular  in  shape, 
its  proximal  end,  that  for  the  partial  articulation  of  the  fibula, 
the  stoutest.  The  anterior  or  dorsal  surface  is  concave  throughout, 
with  its  margins  elevated;  the  posterior  or  plantar  surface  is  nearly 
flat  above.  The  fibular  surface  joins  the  calcaneal  border  in  a 
little  more  than  a  right  angle;  this  surface  is  a  little  broader  from 
side  to  side  than  from  back  to  back,  is  gently  concave,  with  its  plane 
rectangular  to  the  anterior  surface.  The  large  tibial  articular 
surface  is  oblique  to  the  greater  plane  of  the  bone,  as  also  to  the 


REPTILIA:   VARANOSAURUS  107 

antero-posterior  plane.  It  is  broader  above  and  more  convex  on 
the  anterior  side.  The  outer  articular  surface,  for  the  calcaneum, 
is  divided  by  a  deep  transverse  groove  near  its  lower  third,  which 
in  apposition  with  a  similar  but  less  deep  groove  on  the  inner  side 
of  the  calcaneum  forms  the  canal  for  the  perforating  artery,  whose 
posterior  orifice  is  almost  wholly  within  the  astragalus.  Below 
the  groove  there  is  only  a  narrow  surface  for  union  with  the  calca- 
neum. The  distal  surface  is  divided  into  two  facets,  the  outer 
oblique  one  for  articulation  with  the  fourth  tarsale,  the  inner  or 
longer  one  for  articulation  with  the  centrale  or  its  cartilaginous  rep- 
resentative. These  surfaces  are  nearly  flat. 

The  calcaneum  or  fibulare  (Plate  IV,  Figs.  6,  7)  is  as  broad  as 
long,  somewhat  wider,  but  no  longer  than  the  astragalus.  The 
proximal  border  on  the  inner  side  forms,  with  the  astragalus,  the 
articulation  for  the  fibula,  rather  more  on  this  bone  than  on  the 
astragalus.  The  articular  surface  on  the  inner  side  for  the  astrag- 
alus is  grooved,  as  already  described,  for  the  perforating  canal; 
it  has  an  angular  process  on  the  back  side  projecting  into  the 
emargination  of  the  astragalus  at  the  place  of  the  groove.  The 
distal  articulation  for  union  with  the  fourth  and  fifth  tarsalia 
forms  an  angle  with  the  distal  surface  of  the  astragalus.  The 
outer  border,  that  between  the  fibular  and  tarsal  surfaces,  com- 
prises about  one-third  of  a  circle  and  is  relatively  thin,  much 
more  so  on  the  lower  part. 

Of  the  tarsalia,  the  fifth  and  the  second  are  small,  the  fourth 
the  largest,  the  third  and  first  subequal  in  size.  Each  bone  sup- 
ports exclusively  its  own  metatarsal.  The  fifth  articulates  with 
the  calcaneum,  and  for  a  considerable  extent  the  outer  articular 
facet  of  the  fourth;  the  first  tarsale  articulates  with  the 
centrale  and  the  second  tarsale;  the  fourth  joins  broadly  the 
calcaneum,  and  for  a  considerable  extent  the  outer  articular  facet 
of  the  astragalus;  the  third  tarsale  articulates  with  its  adjacent 
tarsalia  and  with  the  centrale  or  possibly  the  astragalus.  The 
second  tarsale,  of  which  only  a  small  oval  facet  is  seen  from  in 
front,  articulates  proximally  with  the  centrale,  and  laterally  with 
the  adjacent  tarsalia;  the  first  tarsale  is  flattened  and  thinned, 
and  evidentlv  has  much  freedom  of  movement,  since  it  is  invariably 


io8  AMERICAN  PERMIAN  VERTEBRATES 

found  more  or  less  dislocated  from  the  other  tarsal  bones;  its 
outer  border,  that  for  articulation  with  the  second  tarsale,  is 
thickened  and  rounded;  the  upper  border,  meeting  the  other  in 
an  angle,  articulated  with  the  centrale,  while  the  distal  border, 
that  between  the  second  tarsale  and  the  metatarsal,  is  short, 
thin,  and  free;  the  inner  upper  border  is  also  free,  but  is  longer 
and  thicker. 

In  the  articulation  of  the  tarsal  bones  as  described  and  figured, 
a  small  space  is  left  at  the  distal  end  of  the  astragalus,  between 
it  and  the  inner  tarsalia,  which  must  have  been  filled  in  life  by  a 
small  centrale;  but  no  such  bone  has  been  found  in  the  numerous 
specimens  recovered,  some  of  them  with  the  foot  in  nearly  com- 
plete condition.  The  bone,  if  present,  must  have  been  thin  in 
front  view,  rather  wide  perhaps  from  side  to  side.  Because  of  its 
constant  absence  in  the  specimens  studied  I  am  convinced,  as  in 
the  front  foot,  the  bone  remained  unossified  in  life,  represented,  I 
doubt  not,  by  cartilage. 

The  phalangeal  formula,  as  determined  beyond  peradventure, 
is  typically  the  primitive  one,  that  of  the  lizards  and  rhyncho- 
cephalians,  2,  3,  4,  5,  4.  Of  the  metatarsals,  the  first  is  as  broad 
as  long,  with  a  thicker  border  anteriorly  at  its  proximal  end. 
The  next  three  metatarsals  progressively  increase  in  length,  the 
third  rather  the  stoutest  of  all.  They  are  somewhat  imbricated 
proximally,  the  dorsal  margin  overlapping  the  thinner  inner  side 
of  the  next  outer  bone.  The  fifth  metatarsal  is  the  most  slender, 
about  the  length  of  the  second,  and  is  somewhat  divergent  from 
the  fourth;  the  position  in  which  it  is  figured  is  that  shown  by 
several  specimens.  Of  the  proximal  phalanges  the  first  of  the 
fourth  digit  is  the  longest,  the  lengths  decreasing  as  follows  in 
the  others:  iv-i,  iii-i,  v-i,  iv-2,  ii-i,  i-i,  iii-2,  ii-2,  i-2,  iii-3, 
iv~3,  v~3,  v~4.  The  claws  are  long,  considerably  curved,  somewhat 
flattened,  but  not  very  sharply  acuminate.  That  of  the  third 
toe  is  the  largest;  that  of  the  fifth  is  small;  this  is  the  only  bone 
of  the  whole  foot  that  has  not  been  found  in  perfect  articulation. 
The  close  articulation  of  the  digital  bones  shows  clearly  a  distinct 
curvature  inward  or  anteriorly  of  the  second,  third,  and  fourth 
toes,  and  as  distinctly  outward  of  the  fifth  toe;  the  first  must  have 


REPTILIA:    VARANOSAURUS  109 

been  nearly  straight.  Altogether  the  foot,  like  the  hand,  was  of 
a  rather  swift-running  terrestrial  crawling  animal,  showing  no 
indications  whatever  of  aquatic  habits. 

Restoration  (Frontispiece). — The  mounted  skeleton  of  Vara- 
nosaurus,  as  shown  in  the  photograph,  is  composed,  save 
the  skull,  almost  exclusively  of  a  single  individual,  of  which  the 
bones  were  found  in  almost  complete  articulation  from  the  frag- 
mentary skull  to  the  forty-seventh  caudal  vertebra.  The  left 
hind  foot  was  incomplete  and  has  been  restored  from  another 
specimen,  as  also  the  right  front  foot,  which  is  that  of  another 
skeleton,  the  bones  of  the  left  front  foot  occurring  in  a  more  or  less 
disturbed  condition.  Several  of  the  spines  of  the  anterior  dorsal 
vertebrae  were  broken  off  and  lost,  as  protruding  from  the  block 
of  the  matrix;  they  have  been  replaced  by  others  from  another 
skeleton  agreeing  accurately  with  them  save  for  the  complete 
spines.  The  figures  of  the  plates,  however,  are  made  exclusively 
from  the  original  specimen.  A  number  of  the  ribs  in  the  mounted 
skeleton  are  made  of  plaster-of-paris,  copies  of  the  real  ribs  found 
in  position,  but  which  could  not  be  extricated  from  the  hard  matrix 
upon  which  they  were  lying  without  destroying  them;  three  or 
four  of  the  most  anterior  ones  are  conjectural ;  these  will  be  replaced 
by  real  ribs,  since  discovered  in  other  skeletons  from  this  region. 
The  skull,  as  stated,  is  that  of  another  skeleton,  that  to  which  the 
third,  fourth,  fifth,  and  sixth  vertebrae  of  the  mounted  skeleton 
belongs.  In  mounting  the  skeleton,  one  of  Varanus  has  been  used 
as  a  guide  to  the  position.  The  hind  legs  have  been  placed  more 
forward  than  is  usual  in  the  skeletons  of  lizards,  because  of  their 
relative  shortness,  but  the  body  has  been  left  in  a  resting  position 
quite  prone  upon  the  base.  The  skeleton,  as  mounted,  measures 
just  forty-four  inches  in  length. 

RELATIONSHIPS    OF    VARANOSAURUS 

It  is  very  evident  that  Varanosaurus  is  intimately  related  to 
Poliosaurus  Case  and  Poecilospondylus  Case,  the  former  very 
imperfectly  known,  the  latter  known  from  a  considerable  part  of 
the  skeleton.  The  present  genus  seems  to  be  distinct  from  either, 
especially  in  the  shape  of  the  vertebral  centra,  though  I  am  not 


no  AMERICAN  PERMIAN  VERTEBRATES 

quite  satisfied  as  to  the  value  of  this  character.  The  relationships 
of  Varanosaurus  with  Theropleura  Cope,  as  identified  and  figured 
by  Case,  are  very  evident.  But  this  genus  includes  much  larger 
forms  with  very  noticeable  differences  in  the  structure  of  the 
limbs.  And  it  is  also  very  apparent  that  the  genus  Ophiacodon 
Marsh  is  a  nearly  related  genus,  clearly  differentiated,  however, 
by  the  teeth  and  limb  bones,  as  I  identify  them  in  the  following 
pages.  These  five  genera,  then,  in  the  order  of  priority,  Ophiacodon 
Marsh,  Theropleura  Cope,  Poliosaurus  Case,  Varanosaurus  Broili, 
and  Poecilospondylus  Case,  so  far  as  now  known,  are  closely  related 
genera  of  the  family  Poliosauridae,  distinguished  by  characters 
given  on  a  preceding  page.  I  suspect  also  that  Dimetrodon 
navajoicus  Case  will  be  found  eventually  to  belong  in  another 
genus  of  the  same  group. 

The  relationships  of  the  family,  using  Varanosaurus  as  the  type, 
are  in  some  respects  very  evident  with  the  Clepsydropidae,  in 
others  apparently  divergent.  Perhaps  the  chief  relationships  will 
be  found  in  the  pelvis,  and  especially  in  the  pubes.  Both  families 
have  a  distinct  pubo-ischiadic  vacuity;  both  have  the  same  peculiar 
expansion  of  the  pubes,  with  the  outer  border  thickened  and  the 
inner  expanse  horizontal  or  even  convex  above;  both  have  the 
same  disproportionate  size  of  these  bones  as  compared  with  the 
ischia.  On  the  other  hand,  the  Clepsydropidae  have  three  sacral 
vertebrae,  while  the  Poliosauridae  have  but  two.  The  vertebrae 
are  alike  in  the  two  groups,  with  the  same  rib  attachments  and 
transverse  processes.  The  feet,  moreover,  are  quite  similar; 
and  the  spines,  while  of  nearly  uniform  length,  in  Varanosaurus 
are  distinctly  elevated  and  thin,  not  enlarged  at  their  upper  ends. 

Widely  different,  however,  are  the  skulls  in  the  two  groups,  in 
the  elongated  form,  almost  isodont  teeth,  the  incomplete  temporal 
arch,  the  sloping  occiput,  and  the  depressed  form. 

Case  believes  that  the  Poliosauridae  are  the  more  generalized 
of  the  Pelycosauria,  and  in  some  things  they  are,  but  not  in  all; 
the  incompleteness  of  the  temporal  arcade  is  certainly  a  significant 
specialization. 

The  resemblances  between  Varanosaurus  and  the  so-called 
Proganosauria  are  evident;  whether  they  are  really  evidences 


REPTILIA:   VARANOSAURUS  in 

of  genetic  relationships,  or  merely  primitive  or  ''old-fashioned 
characters/'  I  am  not  prepared  to  express  a  decided  opinion,  but 
I  believe  that  they  are  genetic.  Of  the  possession  of  two  temporal 
vacuities  by  Stereosternum  or  Mesosaurus  there  is  no  evidence 
furnished  by  the  numerous  skulls  that  have  been  studied,  and  I 
am  firmly  of  the  belief  that  there  is  but  one.  In  the  elongate 
rostrum  with  posterior  nares  we  have  an  aquatic  modification, 
which  of  course  means  wide  specialization  and  adaptation  to  differ- 
ent conditions.  In  the  vertebrae  there  is  a  distinct  resemblance, 
as  also  in  the  ribs,  which  have  been  described  as  single-headed 
and  attached  to  the  centrum,  but  attached  below  a  transverse  pro- 
cess. I  feel  sure  that  the  mode  of  union  is  like  that  of  Casea, 
and  that  the  ribs  are  really  double-headed,  and  their  massiveness 
is  paralleled  by  the  somewhat  similar  condition  in  Casea.  The 
posterior  ribs  were  probably  more  or  less  anchylosed  to  the  verte- 
brae, as  in  both  Casea  and  Varanosaurus.  In  the  pectoral  girdle 
there  are  but  few  real  differences.  McGregor  thinks  there  is 
no  procoracoid,  but  I  have  little  doubt  but  that  the  structure 
here  is  quite  as  in  the  Pelycosauria;  the  genus  resembles  those 
of  the  Theromorpha  too  closely  to  be  otherwise.  The  scapula  is 
more  expanded,  but  that  is  an  aquatic  adaptation.  The  front 
extremity  seems  to  be  quite  like  that  of  Varanosaurus;  the  expanded 
humeri,  the  entepicondylar  foramen,  the  structure  of  the  tarsus, 
and  probably  that  of  the  feet,  save  the  absence  of  claws.  So, 
too,  the  pelvis  and  hind  extremity  are  very  like.  The  pelvis  has 
an  interval  between  the  pubes  and  ischia  as  in  Varanosaurus,  the 
tarsus  is  almost  identical,  and  the  feet,  save  the  claws,  also.  Upon 
the  whole,  given  a  single  temporal  vacuity,  as  I  am  confident  the 
Proganosauria  had,  I  see  no  reason  why  the  genera  should  not  be 
located  in  the  same  order  with  Varanosaurus,  but  in  a  separate 
suborder,  because  of  their  aquatic  adaptations.  In  any  event  I 
have  not  a  bit  of  faith  in  their  rhynchocephalian  relationships. 

Family  Caseidae 
Williston,  Science,  XXXIII,  631,  1911. 

Crawling  phytophagous   theromorphs  with   short,   broad,   de- 
pressed head,  large  body,  long  tail,  and  short  legs,  from  four  to 


H2  AMERICAN  PERMIAN  VERTEBRATES 

five  feet  in  length.  Skull  short,  depressed,  tuberculate,  with  very 
large  parietal  foramen,  small  lateral  temporal  vacuity,  inclosed 
below,  and  with  blunt  conical  teeth  in  maxillae  and  mandibles,  few 
in  number.  Teeth  on  vomers,  palatines,  and  pterygoids.  Spines 
of  vertebrae  short,  stout,  and  of  uniform  length.  Twenty-four 
presacral  vertebrae,  three  sacrals.  No  cleithrum.  Pubes  not 
longer  than  ischia,  not  projecting  forward  in  an  expanded  plate; 
no  pubo-ischiadic  vacuity.  Ribs  very  large  and  heavy;  no  ventral 
ribs.  Feet  pentedactylate. 

CASEA 
Williston,  Jour.  Geol.,  XVIII,  590,  1910. 

Casea  Broilii  Williston,  ibid.    Plates  XIV-XXIV. 

Skull. — But  a  single  skull  of  Casea1  has  so  far  been  detected  in 
the  blocks  of  matrix,  a  part  of  specimen  No.  656,  and  that  not  in 
the  most  satisfactory  condition.  It  was  found  closely  crowded 
below  the  jaws  of  a  Cacops  and  the  pectoral  girdle  and  anterior 
limbs  of  a  Varanosaurus,  and  was  separable  with  difficulty  from  the 
rather  hard,  concretionary  matrix.  The  skull  is  a  little  depressed 
and  somewhat  skewed  to  the  right,  the  palate  pressed  upward 
and  to  the  left.  The  nasal  region  is  not  quite  complete,  especially 
of  the  right  side,  and  the  temporal  arch  of  the  left  side  was  broken 
and  the  parts  somewhat  displaced,  so  that  they  cannot  be  accurately 
readjusted.  I  give  several  figures  of  the  skull  as  I  have  partially 
reconstructed  it  after  careful  study  and  measurements.  For- 
tunately the  mandibles  are  quite  perfect.  The  skull  in  many 
respects  is  remarkable,  presenting  no  decisive  relationships  with 
any  known  form,  though,  of  course,  because  of  the  single  temporal 
vacuity,  allying  the  genus  and  family  more  or  less  with  the  true 
Pelycosauria.  Unfortunately  in  the  present  skull,  as  in  others  of  the 
remarkable  deposit  in  which  these  skeletons  were  found,  the  sutures 
for  the  most  part  cannot  be  made  out,  or,  if  so,  only  conjectural!}'. 
I  find  by  careful  examination  with  a  lens  indications  of  some  of 
them,  and  it  is  not  at  all  improbable  that  with  more  material  for 

1  Since  this  was  written  a  second  one  has  been  found,  but  has  not  been  prepared. 


REPTILIA  :   CASEA 


113 


comparison  the  structure  of  the  skull  will  be  finally  determined 
with  accuracy  and  completely.  Of  the  material  secured  from  this 
bone-bed  there  yet  remains  fully  one-half  inclosed  in  large  blocks 
of  matrix,  and  it  is  very  probable,  indeed  almost  certain,  that 
several  skeletons  of  this  form  will  yet  be  found  among  them.  For 
this  reason,  with  the  single  skull  I  have  not  thought  it  worth  while 
to  give  hypothetical  sutural  lines,  or  attempt  to  discuss  its  intimate 
structure.  The  skull  is  remarkably  broad  and  flat,  concave  above 


FK..  _\S. 


broilii  \Yillislon.     Skull,  from  above,  natural  size. 


transversely  as  preserved,  perhaps  in  life  less  so  or  nearly  flat.  The 
nasal  region  is  protuberant  and  bulbous,  overhanging  the  teeth  both 
in  front  and  on  the  sides;  there  is  an  enormous  parietal  foramen, 
la  rtzer  even  proportionally  than  in  Diadectes,  and  the  largest  I 
know  in  any  vertebrate;  the  single  vacuity,  clearly  the  lower  one,  is 
not  large,  and  is  invisible  from  above;  and  the  teeth  are  remarkable 
for  their  large  size,  small  number,  and  obtusely  conical  shape— 
they  are  evidently  phytophagous.  The  upper  surface  of  the  skull 
-ongly  rugose  for  a  zygocrotaphic  reptile.  The  rugosities  are 


H4  AMERICAN  PERMIAN  VERTEBRATES 

oval  or  rounded  eminences,  separated  by  irregular  pits  or  valleys. 
The  width  between  the  temporal  vacuities  is  very  great,  only  a 
little  less  than  is  the  length  of  the  skull.  Indeed,  so  markedly  cotylo- 
saurian  is  the  shape  of  the  skull  and  so  noticeable  are  the  rugosities, 
that  before  the  temporal  vacuities  had  been  worked  out  I  con- 
cluded, notwithstanding  the  skeletal  characters,  that  the  animal 
was  a  real  cotylosaurian.  However,  notwithstanding  these  resem- 


FIG.  29. — Casea  broilii.     Skull,  from  below,  natural  size. 

blances,  and  others  of  the  pelvis,  there  are  other  characters  quite 
at  variance  with  those  of  the  Cotylosauria. 

The  width  between  the  orbits  is  also  very  great,  fully  one-half 
the  width  of  the  skull  in  its  widest  place.  The  parietal  foramen 
is  situated  just  back  of  a  line  drawn  through  the  posterior  margins 
of  the  orbits,  and  sutural  lines  seem  to  indicate  that  the  frontal 
bones  border  it  in  front.  Neither  temporal  vacuity,  as  stated,  is 
quite  complete,  and  that  of  the  right  side  as  preserved  is  smaller 
than  that  of  the  left;  possibly  in  my  reconstruction  I  have  made  it 
a  trifle  too  long.  The  quadrate  of  the  left  side  had  been  pressed 


REPTILIA:  CASEA  115 

back  a  little,  and  that  of  the  right  a  little  forward.  I  have  equalized 
their  positions  in  my  drawings  to  correspond  with  the  cotylar  sur- 
faces of  the  united  mandibles.  The  upper  and  anterior  borders 
are  quite  perfect  and  the  anterior  part  of  the  right  jugal  arch  is 
undistorted  on  the  right  side.  Each  posterior  angle  of  the  skull 
roof  is  extended  strongly  backward,  outward,  and  then  downward, 
and  is  attached  to  the  posterior  margin  of  the  quadrate.  Below 
there  is  an  interval  between  this  extension  and  the  neck  of  the 
quadrate,  which  seems  to  be  analogous  with  the  quadrate  foramen. 
The  postorbital  bar  is  nearly  vertical,  with  a  gentle  convexity  out- 


FIG.  30. — Casea  broilii.     Skull,  from  the  side,  natural  size. 

ward.  It  is  rather  narrow,  about  one-fourth  the  width  of  the  orbits 
antero-posteriorly.  The  orbits  are  very  large;  they  look  almost 
directly  outward  and  a  little  forward;  they  are  a  little  longer  than 
high,  and  a  little  deeper  posteriorly.  Their  anterior  margins  above 
reach  nearly  as  far  forward  as  the  front  end  of  the  maxillae.  On 
neither  side  is  the  narial  opening  quite  complete,  their  superior 
and  posterior  margins  more  or  less  broken  away,  but  it  is  not 
probable  that  they  are  much  smaller  than  I  have  figured  them. 
The  width  of  the  skull  in  front,  just  in  front  of  the  orbits,  is  dis- 
tinctly greater  than  the  width  between  the  front  ends  of  the 
maxillae  immediately  below,  from  which  it  follows  that  the  anterior 
part  of  the  skull  overhangs  the  teeth,  and  the  nares  are  quite  in- 


u6  AMERICAN  PERMIAN  VERTEBRATES 

visible  from  above;  their  orifices  looking  somewhat  downward. 
The  premaxillae  project  strongly  forward  and  upward  to  meet  the 
projecting  nasals.  The  skull  also  is  deepest  in  front  of  the  orbits, 
indicating  a  large  nasal  cavity,  which  perhaps  may  have  been  of 
service  in  the  same  way  that  the  large  nasal  cavity  of  Ambly- 
rhynchus  is;  indeed,  in  general  shape  the  skulls  of  these  two  animals 
have  a  curious  resemblance.  The  premaxillae,  which  were  found 
attached  to  each  other  and  somewhat  disconnected  from  the  maxil- 
lae, have  each  two  large  teeth,  in  the  articulated  position  directed 
downward  and  not  at  all  forward.  The  narrow  plate  back  of  them 
is  nearly  horizontal,  while  the  attenuated  nasal  processes,  as  stated, 
curve  upward  and  forward.  The  maxillae  are  broad  and  stout 
in  front,  narrower  and  thinner  below  the  orbits.  Each  has  nine 
teeth,  the  four  posterior  ones  small.  The  occiput  is  broad,  slop- 
ing downward  in  the  middle,  and  is  markedly  concave  from  side 
to  side.  The  roof  bones  of  the  skull,  doubtless  the  dermoccipitals, 
extend  downward  and  backward  broadly  in  the  middle  to  the  upper 
margin  of  the  foramen  magnum;  the  rounded  and  thickened  border 
each  side  roofing  over  a  narrow  post-temporal  vacuity.  The 
occipital  condyle  is  small,  with  a  distinct  pit  in  the  middle,  and,  as 
in  other  American  Permian  reptiles,  is  composed  exclusively  of  the 
basioccipital.  The  foramen  magnum  is  rather  large,  bounded 
broadly  on  the  sides  by  the  exoccipitals,  above  by  the  cartilage 
supraoccipital.  The  exoparoccipitals1  form  broad,  gently  concave 
plates,  articulating  distally  with  the  underside  of  the  angular  roof 
extensions,  doubtless  the  tabulare  or  squamosal.  The  quadrates 
are  visible  for  most  of  their  extent.  They  are,  as  in  other  Texas 
Permian  reptiles,  somewhat  fan-shaped  bones  sloping  downward, 
inward,  and  forward,  the  upper  margin  articulating  with  the  roof- 
bones  in  front  of  the  broad  paroccipital,  and  probably  also  with 
the  distal  end  of  the  same  bones.  They  reach  anteriorly  nearly 
as  far  forward  as  the  hind  margin  of  the  orbits.  Their  cotylar 
surface  is  transverse,  broader  internally  than  externally. 

The  palate  bones  are  so  much  confused  in  the  specimen  that  only 
the  more  important  characters  can  be  made  out.  The  vomers  are 

1  V.  Huene  is  in  error  in  saying  that  the  term  paroccipital  was  proposed  by  Huxley. 
It  was  proposed  by  Owen  in  1838  and  should  take  precedence  over  opisthotic,  a  term 
iintroduced  by  Huxley  many  years  later  (1864). 


REPTILIA:  CASEA  117 

united  with  each  other  in  the  middle  line,  at  least  in  front,  and  have 
on  each  side  a  row  of  small  teeth,  double,  perhaps  triple,  behind. 
The  pterygoids  are  separated  in  the  middle  line,  how  broadly  I 
cannot  determine.  I  can  distinguish  no  teeth  on  them,  but  later- 
ally, doubtless  on  the  palatines,  there  are  several  rows;  this  part 
is  not  complete  on  either  side,  and  I  cannot  be  sure  there  was  no 
posterior  palatine  foramen,  but  in  all  probability  there  was  none. 
On  the  transverse  part  behind,  the  part  which  abutted  freely  against 
the  mandible,  and  corresponding  to  the  transverse  bone,  if  distinct, 
there  are  also  evidences  of  teeth,  but  I  cannot  say  how  many.  Pos- 
teriorly the  pterygoids  send  back  a  broad  plate,  as  in  other  Permian 
reptiles,  to  articulate  with  the  lower  inner  side  of  the  quadrates  lying 
along  the  anterior  inner  expansion  of  the  quadrate.  In  Labido- 
saurus  and  Limnoscelis,  at  least,  this  anterior  expansion  of  the 
quadrate  is  visible  above  and  to  the  inner  side  of  the  pterygoid 
process,  but  in  Casea  the  quadrate  slopes  outwardly,  the  pterygoid 
lying  along  in  its  inner  margin.  I  cannot  distinguish  the  stapes 
with  certainty. 

The  basioccipital  is  a  broad,  flat  plate,  narrowed  behind  for  the 
condyle.  It  is  quite  smooth,  and  without  processes.  It  is  some- 
what detached  in  the  specimen,  and,  as  figured,  evidently  comprises 
the  basioccipital  only,  and  not  the  basisphenoid,  of  which  I  find 
no  certain  evidence.  In  front  of  the  basioccipital  there  is  a  tri- 
angular cavity,  from  which  the  basisphenoid  may  have  been  lost. 
On  each  side  of  the  basioccipital  there  appears  to  be  a  large  foramen, 
the  jugular.  Each  pterygoid  sends  up  a  broad  plate,  above  the 
inner  side  of  the  transverse  process,  to  the  roof,  which  it  joins  oppo- 
site the  large  pineal  foramen,  forming  the  side  of  the  brain  case,  and 
continuous  with  the  brain  walls  posteriorly.  This  plate,  of  course, 
must  represent  the  epipterygoid,  springing  as  it  does  from  the  ptery- 
goid, a  bone  supposed  to  be  distinct  from  the  alisphenoid  by  Baur 
(orbitsphenoid  ?  Gaupp). 

Mandibles. — Both  mandibles  were  found  nearly  in  place  in 
articulation  with  the  cranium,  and  both  are  very  perfectly  pre- 
served and  prepared.  Together  they  form  a  broad  V,  nearly  in 
the  shape  of  an  equilateral  triangle.  The  two  sides  meet  in  a 
firm  but  small  symphysis,  which  includes  the  anterior  ends  of 


n8  AMERICAN  PERMIAN  VERTEBRATES 

the  splenials.  The  coronoid  is  rather  low,  rounded,  and  thin. 
Reaching  as  far  back  as  the  teeth  is  the  large  opening  of  the  inner 
side.  The  articular  was  free  on  one  side;  it  is  a  small  bone,  with- 
out an  anterior  or  pre-articular  process,  concave  on  the  upper 
surface  for  the  quadrate.  There  is  no  post-articular  process. 
The  sutural  surface  for  the  union  of  the  articular  bone  is  nearly 
vertical,  and  shows  a  distinct  suture  running  through  the  middle 
between  the  angular  and  surangular  bones,  both  of  which  reach 
quite  to  the  hind  end  of  the  mandible.  Below  and  in  front,  the 
pre-articular  borders  the  lower  margin,  as  usual,  of  the  internal 
vacuity. 

Teeth. — The  teeth  of  Casea  are  very  characteristic,  unlike  any 
that  have  hitherto  been  made  known  from  the  American  Permian. 
There  were  eleven  on  each  side  above  and  below:  two  on  each 
premaxilla,  nine  on  each  maxilla,  and  eleven  in  each  dentary. 
The  anterior  six  of  each  jaw  are  materially  larger  than  the  posterior 
five,  the  last  of  which  are  very  small.  The  two  premaxillary 
teeth  and  the  first  four  of  the  maxilla  and  front  six  of  the  mandibles 
are  very  stout,  conical,  nearly  circular  at  their  base,  but  more 
rounded  at  the  apex,  and  perhaps  a  little  flattened  from  within 
outward.  They  are  somewhat  pleurodont  in  their  attachment, 
but  probably  have  roots  firmly  inserted  in  the  bone.  Those  of 
the  upper  jaws  are  vertical  in  position,  while  the  first  six  or  more 
of  the  mandible  are  more  or  less  prognathous,  the  anterior  ones 
directed  outward  and  forward  at  an  angle  of  forty  degrees  or  more. 
None  of  the  teeth  have  a  sharp  apex,  and  the  rows  are  almost 
continuous,  the  base  of  the  crowns  almost  touching.  The  teeth 
are  evidently  phytophagous. 

Presacral  vertebrae. — The  presacral  series  comprises  twenty- 
four,  all  found  in  close  articulation  with  skull  and  sacrum  and  a 
considerable  part  of  the  tail  in  specimen  No.  657.  The  vertebrae 
shown  in  Plate  XV  are  the  connected  series  of  specimen  No.  655, 
from  the  eighth  to  the  sacrum,  with  a  disconnected  third  vertebra. 
The  first  seven  figured  in  Plate  XIV  are  of  specimen  No.  657. 
The  vertebrae  of  No.  655  had  been  prepared  and  drawn  in  the 
confident  expectation  that  the  series  would  be  found  to  be  com- 
plete, an  expectation,  however,  which  resulted  in  disappointment. 


REPTILIA:  CASEA  119 

So  far  as  this  series  can  be  compared  with  that  of  No.  657,  many 
of  which  have  not  yet  been  cleaned  from  the  rather  hard  incrusting 
matrix,  they  agree  absolutely,  the  vertebrae  of  No.  657  being 
possibly  a  trifle  larger  than  those  of  No.  655.  The  second  presacral 
of  No.  657  is  shown  in  Plate  XIV,  Fig.  2.  The  vertebrae  through- 
out are  easily  distinguishable  from  those  of  all  other  genera,  save 
Trispondylus  perhaps.  Very  remarkable  is  the  disparity  in  size 
between  the  most  anterior  and  the  most  posterior  of  the  presacral 
series,  a  difference  so  great  that  had  the  vertebrae  been  found  dis- 
connected and  isolated,  they  would  not  have  been  associated  in 
the  same  individual — the  diameters  of  the  third  vertebrae  being 
at  least  a  third  less  than  those  of  the  first  presacral,  as  may  be  seen 
by  comparison  of  the  axis  shown  in  Plate  XIV,  Fig.  i,  with  the 
second  presacral  of  the  same  individual  shown  in  same  plate, 
Fig.  2.  The  centrum  of  the  first  presacral  is  only  a  little  broader 
than  long,  concave  below,  "pinched  in"  on  the  sides  so  as  to  give 
a  rounded,  lower  border,  somewhat  keel-like,  but  with  no  indication 
of  the  median  fossa,  so  characteristic  of  the  caudal  centra.  The 
centra  become  rather  rapidly  narrower,  the  tenth  or  eleventh 
presacral  being  nearly  twice  as  long  as  broad,  deeply  concave  on 
the  sides  but  not  keel-like  below.  The  length  begins  to  diminish 
noticeably  after  the  twelfth,  or  the  one  bearing  the  longest  ribs. 
Thenceforward  the  centra  diminish  gradually  in  size,  both  trans- 
versely and  longitudinally,  as  will  be  seen  by  comparison  of  the 
third  with  the  last  in  Plate  XV.  The  spines  are  of  nearly  uniform 
length  throughout,  perhaps  a  little  shorter  anteriorly.  They  are 
oval  in  cross-section,  and  a  little  dilated  at  the  extremity,  the  top 
subcircular  in  the  most  posterior  ones,  elongated  oval  in  the  middle 
and  anterior  ones,  and  beginning  with  the  tenth  or  eleventh 
presacral  they  become  relatively  more  dilated  antero-posteriorly 
through  the  thoracic  region.  The  zygapophyses  are  broad  and 
flat  posteriorly,  narrower  anteriorly,  their  articular  surfaces  looking 
at  only  a  moderate  angle  outward  or  inward.  The  centra  are, 
of  course,  deeply  conically  concave,  with  a  narrow  continuous 
notochordal  canal  through  the  middle.  The  figures  of  the  first 
seven  vertebrae  were  made,  as  stated,  from  another  specimen, 
No.  657.  The  matrix  of  this  specimen  is  unusually  hard  and  the 


120  AMERICAN  PERMIAN  VERTEBRATES 

spines  of  one  or  two  of  the  vertebrae  could  not  be  recovered  entire, 
nor  could  the  smaller  bones  of  the  atlas  be  worked  out.  The 
spines  of  these  vertebrae  are  a  little  less  dilated. 

As  far  forward  as  the  sixth  or  seventh  vertebra  back  of  the 
skull  the  transverse  processes  are  much  alike,  standing  out  hori- 
zontally from  the  sides  of  and  a  little  below  the  anterior  zygapo- 
physes,  a  little  thickened  at  the  extremity.  Their  length  increases 
gradually  and  slightly  to  the  eleventh  or  twelfth  presacral  and 
are  thence  nearly  uniform  to  the  fifth,  where  they  become  less 
stout,  a  little  shorter,  and  are  directed  more  downward.  This 
slight  distinction  may  be  sufficient  to  distinguish  these  five  verte- 
brae as  cervical;  there  are,  of  course,  no  other  characters.  Back 
of  the  fifth  postcranial  the  centra  are  about  the  same  length  below 
as  above;  the  third  and  fourth  have  the  lower  border  distinctly 
shorter  than  the  length  at  the  upper  part  of  the  centra.  This 
diminished  shortness  seems  to  be  entirely  normal  in  the  single 
series.  In  none  of  the  presacral  vertebrae  of  the  three  series  have 
any  intercentra  been  found,  nor  is  there  much  space  for  them  in 
the  intervals  between  the  centra.  The  presence  of  intercentra 
at  the  base  of  the  tail  and  between  the  sacral  vertebrae  is,  however, 
sufficient  evidence  of  their  existence  in  life  throughout  the  series; 
but  they  were  probably  quite  small  in  the  presacral  series  and  may 
not  have  been  well  ossified  throughout. 

Axis. — The  axis  has  a  remarkably  stout  spine,  as  shown  in 
Plate  XIV,  Figs,  i,  ib.  Small  zygapophysial  articulations  were 
probably  present  on  the  sides  in  front,  but  the  border  of  the  speci- 
men was  slightly  injured  here  in  preparation.  The  spine  is  nearly 
as  long  antero-posteriorly  as  the  centrum,  in  the  shape  of  an  obtuse 
wedge,  the  end  rounded,  its  front  border  a  little  thinner  than  the 
hind  one.  The  transverse  processes  are  apparently  complete. 
They  are  short,  and  are  situated  lower  down  than  in  the  following 
vertebrae;  the  rib,  which  was  not  preserved  with  the  specimen, 
was  doubtless  small  and  short.  All  parts  of  the  atlas  were  pre- 
served in  the  specimen,  but  because  of  their  small  size  only  the 
odontoid  could  be  extricated  from  the  matrix,  as  shown  in  the 
figure.  It  differs  very  materially  from  the  odontoid  of  the  Clepsy- 
dropidae  or  Poliosauridae.  It  is  relatively  large,  thinned  below, 


REPTILIA  :  CASEA  1 2 1 

transversely  concave  on  the  upper  surface,  and  has  a  conical 
cavity  on  the  posterior  side,  which  in  life  was  in  apposition  with  the 
concavity  of  the  axis,  and  was  for  the  notochord,  which,  however, 
did  not  extend  through  the  bone.  Very  evidently  the  intercentra 
of  both  the  atlas  and  the  axis  were  relatively  large  bones. 

Ribs  (Plate  XVII). — The  ribs  of  Casea  are  remarkable  for  their 
size  and  length.  They  were  found  in  all  three  specimens  in  posi- 
tion as  far  forward  as  the  sixth  or  the  seventh;  the  more  anterior 
ones  were  not  recovered  and  have  necessarily  been  restored  in  the 
mounted  specimen,  and  I  suspect  that  they  were  somewhat 
longer  on  these  anterior  vertebrae  than  they  have  been  restored. 
The  first  four  presacral  vertebrae  have  the  ribs  firmly  co-ossified 
with  the  arch  and  centrum,  leaving  a  small  foramen  between  head 
and  tubercle.  The  ribs  of  the  fifth  presacral  were  less  firmly 
united  and  in  the  two  specimens  examined  had  dropped  away, 
though  their  union  is  seen  to  be  a  sutural  one.  The  ribs  of  the 
first  presacral  are  rather  slender  and  are  directed  a  little  forward 
and  upward,  their  extremities  being  higher  than  their  capitula. 
The  next  three  pairs  increase  rapidly  in  length;  they  are  directed 
outward,  a  little  forward,  and  then  curve  downward  strongly  at 
their  extremities.  Like  all  the  preceding  ribs  preserved  they  are 
remarkably  thick  and  stout.  The  longest  ribs  of  the  series  occur 
at  the  middle  of  the  presacral  series.  They  are,  as  preserved,  for 
the  most  part  quite  regularly  curved,  nearly  cylindrical,  very 
stout,  tapering  a  little  distally.  The  tubercular  part  is  not  sharply 
indicated  as  it  lies  against  the  end  of  the  diapophysis,  nor  is  there 
a  distinct  facet  on  any  of  the  centra  for  the  union  of  the  capitulum, 
which  must  have  been  quite  in  the  intercentral  space,  a  little 
below  the  middle  of  the  centrum,  leaving  a  very  considerable 
foramen  in  the  articulated  condition.  The  distal  end  is  truncate, 
indicating  a  cartilaginous  continuation,  but  this  continuation  was 
probably  very  short,  since  the  ribs  in  articulation  for  the  most 
part  curve  inward  at  the  lower  end  and  may  be  compared  with 
the  shorter  ribs  and  costal  ribs  of  the  lizards  combined.  Evidently 
the  underside  of  the  body  between  the  ribs  was  quite  flat,  other- 
wise the  belly  would  have  been  strongly  protuberant  below  the 
level  of  the  pelvis  and  pectoral  girdle.  There  is  not  the  slightest 


122  AMERICAN  PERMIAN  VERTEBRATES 

indication  in  any  of  the  recovered  specimens  of  ventral  ribs,  such 
as  occur  so  commonly  in  Varanosaurus  and  other  genera  of  the 
Poliosauridae,  and  it  is  assumed  that  were  they  existent  some 
indications  of  them  would  have  been  found  in  the  various  specimens. 

Sacrum  (Plate  XVI,  Fig.  i;  Plate  XX,  Fig.  6;  Plate  XXIII, 
Fig.  6). — The  sacrum  of  Casea  is  composed  of  three  vertebrae, 
differing  from  those  immediately  preceding  and  succeeding  chiefly 
in  their  short  and  expanded  ribs.  These  vertebrae  articulate 
freely  with  each  other,  and  have  free,  though  small,  intercentra 
below.  The  centra  are  convex  from  side  to  side  below,  compressed 
on  the  sides.  The  spines  are  proportionately  a  little  stouter 
than  those  immediately  preceding  the  sacrum,  their  upper  extremity 
nearly  as  broad  as  long.  The  ribs  are  attached  quite  like  the  pre- 
ceding ones,  but  are  stouter,  and  like  the  three  or  four  succeeding 
pairs,  by  a  short  head  reaching  below  the  middle  of  the  centrum 
and  articulating  in  part  with  the  preceding  centrum  across  the 
intercentral  space.  The  tubercular  part  is  very  stout  and  heavy, 
extending  high  up  on  the  arch.  Between  the  head  and  tubercle 
the  small  foramen  is  persistent,  as  in  the  posterior  lumbar  vertebrae. 
The  shaft  of  the  ribs  is  subcylindric  or  prismatic,  dilated  at  about 
the  middle  part  into  a  broad  flattened  plate,  broadly  convex  out- 
wardly and  curved  downward  so  that  its  lower  border  is  about 
on  a  level  with  the  lower  margin  of  the  centra.  The  expanded  ends 
of  the  first  and  second  pairs  are  about  equal  in  size;  that  of  the 
third  is  smaller,  but  little  more  than  half  that  of  the  first.  It  is 
stouter  at  its  extremity  and  does  not  descend  quite  as  far.  The 
extent  of  these  three  ribs  appears  to  be  slightly  greater  than  the 
greatest  extent  of  the  ilia  antero-posteriorly.  Their  union  with  the 
ilia  was  a  comparatively  loose  one,  chiefly  ligamentous,  the  ends  of 
the  ribs  merely  touching  the  ilia,  which  show  no  sutural  markings 
for  their  union. 

Caudal  vertebrae  (Plate  XVI). — No  single  tail  yet  recovered  is 
quite  complete.  That  of  specimen  No.  655  comprises  seven  verte- 
brae, as  figured  in  Plate  XVI,  Fig.  i ;  that  of  No.  656  comprises 
about  twenty  in  a  continuous  series  with  the  sacrum  and  complete 
precaudal  series;  the  incomplete  tail  of  No.  657  has  not  been  freed 
from  the  matrix,  but  has  twenty-two  vertebrae  in  the  series  con- 


REPTILIA:  CASEA  123 

tinuous  with  the  sacrum;  a  fourth  specimen  found  isolated,  but 
which  in  all  probability  belongs  with  those  of  the  other  skeletons, 
includes  a  connected  series  of  caudal  vertebrae,  eighteen  in  number, 
beginning  just  where  the  spine  is  becoming  obsolete.  This  last 
specimen  has  been  used  in  connection  with  the  series  of  No. 
657.  It  is  possible  that  one  or  two  vertebrae  may  have  intervened 
between  the  vertebrae  as  united,  but  this  is  not  very  probable, 
since  the  junction  is  made  where  all  the  characters  seem  to  agree. 
The  last  vertebra  of  No.  658  measures  six  mm.  in  transverse 
diameter;  continuing  the  same  taper,  seven  vertebrae  have  been 
modeled  from  plaster  and  added  in  the  restoration,  making  the 
approximate  number  of  vertebrae  in  the  entire  tail  fifty  in  number, 
or  almost  the  same  as  that  of  Varanosaurus,  where  the  complete,  or 
nearly  complete,  series  of  a  single  individual  was  found  intact. 
The  tail,  however,  as  a  whole,  like  the  preceding  part  of  the  spinal 
column,  is  stouter  than  in  Varanosaurus,  and  less  compressed. 

Co-ossified  ribs,  or  vestiges  of  ribs,  are  found  on  the  first  seven 
or  eight  of  the  series.  The  first  three  pairs  extend  quite  the  width 
of  the  sacrum,  thence  decreasing  rapidly  in  length  till  they  are 
mere  tubercles.  The  second  pair,  the  largest,  are  directed  outward, 
and  then  horizontally  backward,  to  a  point  about  opposite  the 
middle  of  the  next  vertebra.  The  third  pair,  more  slender,  are 
directed  outward,  with  an  anterior  curvature,  barely  escaping  the 
tips  of  the  preceding  ones.  Like  the  preceding  ribs,  the  caudal 
ribs  are  double-headed,  and  are  co-ossified  with  arch  and  centrum ; 
on  the  hinder  ones  the  tubercle  seems  to  be  in  large  part  attached 
to  the  centrum.  The  spines,  so  far  as  they  were  recovered  from 
the  matrix,  become  successively  shorter,  terminating  as  a  mere 
tubercle  at  about  the  eighteenth  vertebra;  and  they  are  quite  thin 
at  the  extremity,  slightly  more  thickened  anteriorly.  Beginning 
with  the  third  in  No.  656,  the  fourth  in  No.  655,  the  underside 
of  the  centrum  has  a  distinct  longitudinal  median  groove  or 
fossa,  decisively  distinguishing  the  genus  from  all  others.  This 
fossa  is  narrow  and  well  marked,  extending  to  the  last  of  the 
series  as  preserved,  and  doubtless  quite  to  the  extremity  of  the 
tail.  From  the  third  or  fourth  to  the  seventh  or  eighth,  the 
centra  are  very  distinctly  shorter  below  than  above,  and  both 


124  AMERICAN  PERMIAN  VERTEBRATES 

the  specimens  as  preserved  showed  a  downward  curvature  of  the 
tail  in  this  region.  The  last  intercentrum  is  between  the  second 
and  third  caudal  centra,  and  is  of  extraordinary  size,  in  marked 
contrast  with  the  small  ones  found  between  the  sacral  vertebrae. 
Chevrons  begin  in  the  next  interval,  that  is,  at  the  hind  end  of  the 
third  vertebra,  the  usual  place  for  the  chevrons  to  begin  in  the 
Permian  reptiles,  and  several  were  found  in  No.  657  quite  in  posi- 
tion. They  are  rather  short;  those  found  in  position  were  broadly 
and  firmly  connected,  articulated  in  the  intercentral  space,  and 
broadly  connected  proximally.  They  articulate  in  a  very  oblique 
position,  the  upper  posterior  surface  being  grooved  for  more  than 
half  their  length  for  the  lodgment  of  vessels;  some  are  slightly 
expanded  at  the  distal  end.  Other  chevrons  from  succeeding 
vertebrae  are  very  short  and  broad.  From  the  eighteenth  vertebra 
to  the  extremity  the  chevrons  must  have  been  very  small,  which, 
with  the  entire  absence  of  spines,  rendered  the  tail  for  the  greater 
part  of  its  extent  nearly  cylindrical.  The  tail  shows  conclusively 
that  the  animal  was  in  no  degree  whatever  natatorial  in  habit. 

Pectoral  girdle  and  extremity  (Plates  XIX,  XX). — The  material 
of  the  pectoral  girdle  is,  unfortunately,  not  complete.  No  clavicles 
have  yet  been  found  with  either  of  the  specimens;  that  is,  no 
clavicles  which  indubitably  belong  with  this  form.  A  solitary 
interclavicle,  figured  in  Plate  XIV,  Fig.  6,  probably  belongs  with 
this  form,  since  it  cannot  belong  with  either  Varanosaurus,  Cacops, 
Seymouria,  or  Captorhinus,  the  only  other  genera  found  in  the  bone 
deposit.  It  was  found  isolated.  Two  scapulae  were  recovered 
associated  with  specimen  No.  655;  of  the  left  one,  the  upper  end 
is  missing,  and  of  both,  the  anterior  border  is  more  or  less  muti- 
lated. The  interclavicle  figured  differs  materially  from  that 
of  Varanosaurus  in  the  shortness  of  the  posterior  stem,  shortness 
that  would  seem  to  agree  better  with  the  large  flat  trunk  of  this 
genus.  The  specimen  is  shaped  much  like  a  small  spoon,  and  is  not 
quite  complete  on  its  anterior,  dilated  part.  The  dilated  part 
is  concave  on  the  upper  side,  convex  below,  and  is  somewhat 
rugose  on  each  side  for  the  articulation  of  the  clavicles.  The 
posterior  part  is  slender  and  nearly  straight,  a  little  wider  and 
thinner  posteriorly.  The  scapula-coracoid  is  remarkable  for  the 


KEPT  I  LI  A  :  CASE  A  125 

great  development  of  the  coracoid  part,  and  the  relative  slenderness 
of  the  upper,  scapular  part,  which  is  preserved  complete  on  one 
side.  This  part  is  moderately  thick,  convex  internally,  concave 
externally.  The  front  border,  for  about  twenty  millimeters,  is 
thickened  and  rounded,  that  part  above  the  extremity  of  the  clav- 
icle. Below  this  the  border  is  thin,  and  for  the  most  part  is  lost 
in  both  scapulae.  The  glenoid  articulation  is  large  and  well  formed, 
that  on  the  preglenoid  facet  looking  downward,  backward,  and 
outward;  that  on  the  metacoracoid  looking  more  directly  outward 
and  a  little  backward.  The  supracoracoid  foramen  is,  as  usual,  a 
little  below  and  in  front  of  the  margin  of  the  preglenoid  facet. 
I  find  no  supraglenoid  foramen,  either  in  the  supraglenoid  fossa, 
which  is  very  shallow,  or  on  the  outer  side  in  front,  as  in  Dimetrodon 
and  Varanosaurus.  The  very  large  coracoid  turns  inward  hori- 
zontally and  is  a  little  concave  longitudinally.  Sutures  between 
the  coracoid  elements,  or  between  them  and  the  scapula,  are  not 
distinguishable,  but,  in  all  probability,  that  separating  the  meta- 
coracoid, which,  unlike  the  condition  in  Varanosaurus,  is  well 
ossified,  passes  directly  inward  at  about  the  middle  part  of  the 
fossa.  The  fossa  on  the  inner  side,  into  which  opens  the  supra- 
coracoid foramen,  is  rather  short.  Just  back  of  the  metacoracoid 
facet  on  the  upper  border  of  the  bone  there  is  a  rather  prominent 
process  corresponding  with  the  more  prominent  one  in  the  same 
place  in  Dimetrodon.  Possibly  its  presence  is  indicative  of  genetic 
affinity,  since  it  is  absent  in  other  known  scapulae. 

Humerus  (Plate  XX,  Figs.  1-3). — The  humerus,  while  in  general 
resembling  that  of  Varanosaurus,  presents  several  marked  differ- 
ences, distinguishing  the  two  forms  immediately.  The  planes  of 
the  extremities  are  almost  at  right  angles  to  each  other ;  the  slender 
shaft  of  the  bone,  as  seen  from  the  front,  is  distinctly  above  the 
middle;  the  entepicondylar  foramen  is  larger,  and  is  not  situated 
so  close  to  the  inner  margin;  the  ectepicondylar  process  is  broader 
and  more  protuberant,  and  the  entocondylar  dilatation  is  produced 
more  inward  in  a  direct  line,  and  is  thickened.  The  lateral  process 
is  much  stouter  and  projects  more  inward;  the  capitellum  forms 
almost  a  hemisphere,  the  chord  of  its  convexity  looking  forward 
at  an  angle  of  about  forty-five  degrees,  and  its  articular  surface 


126  AMERICAN  PERMIAN  VERTEBRATES 

is  not  at  all  visible  on  the  dorsal  side  of  the  bone,  whereas  the 
trochlear  surface  is  only  a  little  less  conspicuous  on  the  dorsal 
than  on  the  ventral  side.  The  humerus,  moreover,  is  relatively 
much  stouter  and  longer  than  in  Varanosaurus,  whereas  the  femur 
is  distinctly  smaller  and  shorter.  The  resemblance  of  the  bone 
to  the  humerus  of  Trispondylus  is  much  closer  than  to  the  humerus 
of  Varanosaurus,  as  will  be  described  later. 

Both  forearms  of  specimen  No.  655  were  recovered,  the  right 
one  associated  with  humerus  and  hand,  the  left  bones  isolated; 
and  in  addition  a  radius  and  an  ulna  were  found  associated  with  a 
humerus  of  No.  656.  Some  of  these  bones  are  slightly  bent  or 
otherwise  distorted,  and  the  ones  figured  in  Plate  XX,  Fig.  4,  the 
left  bones  of  No.  655,  are  not  quite  as  perfect  as  are  the  right 
ones  of  the  same  specimen,  outlines  of  which  are  given  in  the  accom- 
panying text  figure.  Both  ulna  and  radius  are  longer  bones  than 
are  the  radius  and  ulna  of  Varanosaurus  and  are  not  as  much 
expanded  at  their  extremities.  The  ulna  has  the  inner  border 
nearly  straight,  the  radial  side  deeply  concave;  the  radius  is 
nearly  straight  on  the  ulnar  border,  moderately  concave  on  the 
outer  side.  The  interval  between  the  two  bones  is  much  narrower 
than  in  Varanosaurus. 

The  hand  bones  of  the  right  side  of  specimen  No.  655  were 
found  close  by  the  distal  end  of  the  radius  and  ulna,  but  so  con- 
fused that  their  natural  articulations,  save  in  a  few  cases,  could  not 
be  determined  from  their  positions.  Ten  or  eleven  carpals  were 
more  or  less  attached  together,  the  full  number  of  these;  the  radiale, 
ulnare,  and  pisiform  are  easily  distinguishable  by  their  size  and 
shape.  The  ulnare  resembles  that  of  Varanosaurus  (in  the  restored 
skeleton,  the  bone  is  reversed).  The  radiale  is  smaller  and  more 
rounded  on  its  proximal  surface,  permitting  apparently  greater 
lateral  movement  of  the  hand.  The  intermedium  and  second 
centrale  are  both  rather  small,  and  cannot  be  differentiated  in  the 
single  specimen.  The  fourth  and  fifth  carpalia  were  attached  in 
natural  positions  and  are  de terminable  with  certainty;  the  fifth 
is  of  considerable  size,  as  would  be  expected  from  the  large  size 
of  the  fifth  finger.  The  third  carpale  is  also  in  all  probability 
correctly  placed,  because  of  its  large  size.  The  chief  doubt  is 


REPTILIA:  CASEA 


127 


regarding  the  first  and  second  carpalia  and  the  first  centrale; 
these  three  bones  were  found  closely  attached,  the  centrale  very 
small,  almost  vestigial,  the  first  and  second  so  closely  united  that 
I  am  not  certain  that  more  than  one  is  really  present.  They  are 
all  small.  The  metacarpals  and  phalanges  found  associated  are 
shown  in  the  text  figure  in  un- 
broken lines,  but  with  nothing 
to  guide  in  their  location  save 
that  two  pairs  of  phalanges  were 
found  articulated  as  indicated  in 
the  figure  by  the  plus  sign  placed 
near  the  joint.  That  the  hand 
had  the  primitive  phalangeal 
formula,  2,  3,  4,  5,  3,  there  can 
be  scarcely  a  doubt,  and  I  have 
so  collocated  the  bones.  It  is 
quite  certain  that  both  the  first 
and  fifth  fingers  were  much 
longer  and  better  developed 
than  is  the  case  in  Varanosaurus. 
The  hand,  it  is  seen,  is  very 
much  like  the  foot,  and  fully  as 
large  if  no  larger;  it  was  broad 
and  rather  short,  but  with  strong 
and  powerful  claws,  as  shown  in 
Plate  XIX,  Fig.  4. 

Pelvic  girdle  and  extremity 
(Plates  XXI-XXIII).— The 
pelvis,  preserved  in  three  speci- 
mens, is  perfect  and  almost 
undistorted  in  No.  655.  The 
two  sides  meet  in  a  moderately  firm  horizontal  symphysis,  a 
small  notch  only  at  the  junction  of  the  four  bones  remaining 
unossified  as  a  small  pubo-ischiadic  fenestra.  The  ilium  is  con- 
spicuously different  from  all  those  hitherto  observed  in  the 
American  Permian  in  having  a  prominent  anterior  projection  and 
only  a  small  posterior  one.  It  is  somewhat  helmet-shaped,  con- 


FIG.  31. — Casea  broilii. 
leg,  one-half  natural  size. 


Right  front 


128  AMERICAN  PERMIAN  VERTEBRATES 

tracting  into  a  rather  narrow  neck  just  above  the  acetabulum,  with 
a  rather  deep  notch  posteriorly,  the  antero-posterior  extent  of 
the  bone  below  being  not  quite  as  great  as  that  above.  The  ante- 
rior border  is  thicker  and  much  more  extensive,  the  deepest  part 
being  about  midway  between  the  pubic  symphysis  and  the  superior 
angle.  The  posterior  border  is  U-shaped,  with  nearly  equal  arms. 
On  the  inner  side  the  lower  part  is  convex  antero-posteriorly.  The 
sacral  ribs  doubtless  were  attached  at  their  extremities  by  ligaments 
extending  the  full  length  of  the  bone  above.  The  pubes  and  ischia 
are  not  very  different  in  shape,  and  of  about  equal  size.  The  pubis 
has  a  thin  anterior  margin  in  front  of  the  acetabulum  with  a  dis- 
tinct pectineal  process  near  the  acetabular  margin.  In  articula- 
tion the  two  pubes  leave  a  deep  V-shaped  emargination,  the  thick- 
ened symphysial  margin  confined  to  the  posterior  part  of  the  inner 
border.  The  obturator  foramen  pierces  the  bone  obliquely,  its 
external  orifice  just  within  the  acetabular  margin  on  the  posterior 
two-fifths  of  the  bone.  The  ischium  has  a  thin,  convex  posterior 
margin,  the  two  bones  in  symphysis  showing  only  a  small  V-shaped 
exmedian  excision.  The  thickened  symphysial  margin  is  formed  in 
nearly  equal  parts  by  the  three  bones,  that  of  the  ilium  the  greater. 
The  ilium  has  an  overhanging  process  above.  The  pubo-ischiadic 
suture  passes  directly  inward  at  the  middle  of  the  inferior  margin 
of  the  acetabulum  and  divides  the  horizontal  part  of  the  pelvis 
into  nearly  equal  parts. 

Femur  (Plate  XXII,  Figs.  1-4). — The  femur  is  relatively  short 
in  comparison  with  that  of  Varanosaurus,  but  somewhat  stouter. 
The  head  is  broad  from  side  to  side  above,  thinned  at  the  outer 
posterior  angle.  The  digital  fossa  is  shallow  but  broad.  The 
trochanter  is  prominent,  directed  backward  and  a  little  inward. 
The  shaft  of  the  bone  in  the  middle  is  rather  slender  and  prismatic 
in  shape.  The  fibular  condyle  as  usual  is  much  deeper  antero- 
posteriorly  than  the  tibial,  and  the  latter  is  placed  at  a  sharp  angle. 

Tibia  (Plate  XXII,  Figs.  5,  6).— The  tibia  is  short  and  thickset, 
rather  slender  in  the  middle,  much  expanded  at  either  extremity, 
the  inner  border  gently,  the  outer  border  deeply,  concave.  The 
lower  extremity  is  expanded  somewhat  obliquely  backward  and 
inward,  has  its  articular  surface  broadly  oval,  its  long  diameter  a 


REPTILIA  :  CASEA  129 

half  greater  than  its  lesser.  The  upper  extremity  is  very  broad 
from  side  to  side  with  a  not  very  deep  groove  in  front  between  the 
heavy  cnemial  expansion  and  the  broad  inner  part  of  the  head. 
Anteriorly  the  border  of  the  bone  is  very  gently  concave  in 
profile,  posteriorly  rather  deeper. 

Fibula  (Plate  XXII,  Fig.  7,  8).— The  fibula  is  relatively  short, 
much  expanded  at  either  extremity,  slender  in  the  middle.  The 
outer  border  is  straight  or  gently  convex,  the  inner  deeply  concave. 
The  lower  extremity  is  much  expanded  from  side  to  side,  its  some- 
what convex  border  squarely  truncated;  its  anterior  surface  is 
nearly  flat,  the  posterior  concave  in  the  middle,  the  sides  thicker. 
The  upper  extremity  is  considerably  expanded  obliquely  forward 
and  inward;  convex  on  the  outer  anterior  side,  concave  on  the 
inner;  the  anterior  part  thin,  the  posterior  part  thick;  the  upper 
articular  surface  for  the  most  part  looking  upward,  forward,  and 
inward. 

Foot  (Plate  XXIII).— Two  feet,  both  right  ones,  have  been 
recovered,  belonging  with  specimens  Nos.  655  and  657.  Neither 
is  quite  complete,  the  latter  having  the  bones  very  slightly  smaller 
and  more  slender.  In  both  specimens  the  tarsus  is  completely 
articulated  and  united  with  the  metatarsals.  In  No.  655  the  first, 
in  No.  657  the  fourth  and  fifth  digits  have  the  first  and  second 
phalanges  also  attached.  Four  ungual  phalanges  are  preserved 
in  No.  657;  three  in  No.  655.  In  addition  there  are  four  isolated 
phalanges  in  each  foot.  These  phalanges  I  have  located  in  the 
drawing  as  seems  most  probable,  leaving  four  that  are  unrep- 
resented, indicated  in  the  drawing  by  outlines.  A  sign  indicates 
the  joints  in  which  there  was  no  matrical  contact.  In  No.  655 
the  first  digit  was  lying  in  the  position  shown  in  the  drawing; 
in  No.  657  the  metatarsal  was  divaricated  in  the  matrix,  very 
much  as  in  the  foot  of  Varanosaurus. 

The  foot  as  a  whole  is  very  noticeably  different  from  that  of 
Varanosaurus,  in  the  relatively  greater  size  of  the  tarsus  and  first 
and  fifth  digits.  The  astragalus  is  more  elongated,  narrower 
distally,  and  the  tibial  articulation  is  more  nearly  parallel  to  the 
inner  side;  the  foot  was  placed  at  a  greater  angle  with  the  long 
axis  of  the  foreleg.  The  fibulare  is  also  more  elongated,  and  the 


130  AMERICAN  PERMIAN  VERTEBRATES 

perforating  canal  is  at  a  greater  distance  from  the  distal  ends  of 
the  bones.  In  the  distal  row  the  bones  are  all  decidedly  larger 
but  have  the  same  articulation.  The  centrale  is  well  ossified, 
separating  the  tibiale  from  the  first  tarsale,  more  broadly  in  front 
than  behind. 

The  first  metatarsal  is  a  short,  stout  bone,  about  half  the  length 
of  the  fifth,  which  is  the  longest  of  the  series.  It  bears  a  single 
rather  long  and  stout  phalange  and  a  large  claw.  This  toe  was 
probably  divaricable  in  life.  The  fourth  and  fifth  metatarsals 
are  not  very  different  in  length,  but  the  fifth  is  the  stouter.  The 
claws  (Fig.  4)  are  large,  much  curved,  and  pointed,  with  a  stout 
inferior  tubercle  for  the  insertion  of  the  flexor  tendon.  It  is,  of 
course,  assumed  that  the  phalangeal  formula  is  of  the  primitive 
kind,  as  in  Varanosaurus,  and  I  do  not  think  there  can  be  doubt  of 
this,  although  the  absence  of  three  or  four  phalanges  leaves  the 
positive  proof  of  this  for  future  investigation.  If  my  arrangement 
of  these  phalanges  is  correct  the  fifth  toe  is  but  little  shorter  than 
the  third.  Altogether  it  is  very  certain  that  the  foot  was  broader 
and  stouter  than  that  of  Varanosaurus  and  is  nowise  indicative  of 
climbing  or  even  markedly  cursorial  habits. 

RESTORATION 

The  mounted  skeleton  as  shown  in  the  frontispiece  is,  as  has  been 
explained  in  the  foregoing  pages,  a  composite  of  three  different 
skeletons,  Nos.  655,  656,  657.  Of  No.  655,  from  the  base  of  the 
tail  to  the  seventh  postcranial  vertebra,  the  ribs,  the  scapulae,  right 
foreleg,  left  radius  and  ulna,  pelvis,  the  right  hind  leg,  and  the  left 
femur.  Of  656,  the  skull  and  first  seven  vertebrae;  while  the  tail 
is  in  part  from  another  specimen.  These  various  specimens  in 
the  many  bones  they  have  in  common  agree  perfectly  in  characters 
and  almost  absolutely  in  size,  so  that  the  composition  in  nowise 
affects  the  form  and  appearance  of  the  skeleton.  The  parts  shown 
which  are  more  or  less  conjectural  are  the  first  six  or  seven  pairs  of 
ribs,  the  posterior  chevron  bones,  the  distal  six  caudal  vertebrae, 
and  a  few  of  the  phalanges  of  both  front  and  hind  feet.  The  left 
humerus,  hand,  tibia,  fibula,  and  foot  have  been  modeled  after  the 
right  ones.  As  has  been  explained  there  are  other  skeletons 


REPTILIA:   TRISPONDYLUS  131 

of  this  form  still  inclosed  in  the  blocks  of  matrix  in  the  museum, 
and  sometime  in  the  future,  when  they  are  worked  out,  even  these 
plaster  portions  will  be  replaced  by  actual  specimens.  The  inter- 
clavicle,  as  explained,  was  an  isolated  bone.  The  skeleton  at 
first  sight  impresses  one  with  the  incongruity  between  head  and 
abdomen.  The  head  is  relatively  small  for  so  large  a  reptile  and 
the  trunk  is  relatively  very  large.  The  ribs  are  not  only  large  and 
strongly  curved,  but  they  extend  back  in  unusual  length  almost 
to  the  pelvis.  The  front  legs  are  longer  and  stronger  throughout 
than  the  hind  ones;  the  feet  are  broad  and  flat.  It  is  very  evident 
that  the  creature  was  a  terrestrial  reptile,  not  a  climber.  That 
it  was  herbivorous  in  habit,  the  teeth  show  conclusively,  and  doubt- 
less the  very  large  abdominal  cavity  is  correlated  with  its  food 
habits.  The  head  has  in  shape  a  curious  resemblance  to  the 
aquatic  lizard  Amblyrhynchus,  but  the  resemblance  ends  there. 
The  slender,  cylindrical  tail  forbids  any  assumption  of  aquatic 
habits,  as  do  also  the  long  and  strong  claws.  In  much  probability 
the  animal  was  a  river  plains  inhabiting  type,  perhaps  feeding  upon 
succulent  meadow  vegetation. 

TRISPONDYLUS 
Williston,  Jour.  GeoL,  XVIII,  592,  1910. 

Trispondylus  texensis  Williston,  ibid.    Plates  XXV,  XXVI. 

The  known  remains  of  this  genus  and  species  consist  of  a  single 
specimen  found  intimately  associated  with  the  type  specimen  of 
Trematops  milleri  Williston,  near  the  west  line  of  Craddock's 
ranch,  in  the  vicinity  of  Seymour,  Texas.  The  specimen  was 
exposed  and  more  or  less  broken  and  weathered,  inclosed  in  an 
obdurate  matrix.  The  parts  recovered  are  a  nearly  complete 
right  humerus,  with  attached  radius  and  ulna;  numerous  carpal 
and  hand  bones;  eighteen  vertebrae  in  four  series,  the  first  of 
which  is  in  the  cervical  region,  the  second  more  posterior,  with 
the  distal  end  of  the  interclavicle  attached,  the  third  series  yet 
farther  back,  and  the  fourth  of  eleven,  including  three  caudals, 
three  sacrals,  and  five  lumbars;  the  right  innominate;  the  right 


132 


AMERICAN  PERMIAN  VERTEBRATES 


femur,  and  various  fragments  of  the  pectoral  girdle  and  other 

bones. 

Unfortunately  none  of  the  vertebrae  has  the  spine  complete, 

but  various  fragments  indicate  that  they  were  short.     The  centra 

are  impressed  on  the  sides,  rounded  transversely  below;  the  trans- 
verse processes  are  like  those  of 
Casea,  standing  out  rather 
broadly  from  the  sides  of  the 
arch;  and  yet-attached  ends  of 
ribs  indicate  their  stoutness  and 
mode  of  attachment  as  in  Casea. 
The  posterior  centra  are  notice- 
ably stouter  and  larger  than  the 
more  anterior  ones.  The  two 
most  anterior  vertebrae  are  evi- 
dently  from  not  far  back  of  the 
skull,  probably  the  fifth  and  the 
sixth.  They  are,  as  in  Casea, 
very  much  shorter  than  the  pos- 
terior vertebrae,  so  short  and 
small  that  they  were  at  first 
mistaken  for  median  caudal  ver- 
tebrae. The  centra  are  nearly  as 
broad  as  long,  and  the  transverse 
processes  are  a  little  shorter  than 
the  more  posterior  ones.  Inter- 
centra  are  present  in  a  few  of 
the  intercentral  spaces.  The 
sacrum  is  almost  identical  with 
that  of  Casea,  the  expansion  of 
the  first  pair  of  ribs  nearly  equal 
to  the  combined  widths  of  the 
two  posterior  pairs.  The  three 

attached  proximal  caudals  have  co-ossified  ribs,  and,  so  far  as  they 

are  preserved,  they  seem  to  be  quite  like  those  of  Casea. 

The  humerus  preserved  is  stout,  resembling  that  of  Casea  very 

much.     Between  the  two  bones  the  characters  are  quite  complete, 


FIG.  32. —  Trispondylus  texensis. 
Right  forearm  and  foot,  one-half  natural 
size. 


REPTILIA:   TRISPONDYLUS  133 

save  that  the  ectepicondyle  is  eroded  away.  The  median  process 
on  the  dorsal  side  near  the  proximal  ulnar  angle  is  very  pronounced, 
rounded,  and  roughened.  The  ventral  radial  plane  of  the  lateral 
process,  looking  ventrad,  laterad,  and  distad,  is  flat  and  separated 
from  the  dorsal  surface  by  a  very  distinct  angular  ridge,  very 
characteristic  of  this  genus  and  of  Casea.  The  entocondyle  extends 
nearly  to  the  full  length  of  the  bone,  and  is  thickened,  not  ending 
considerably  before  the  distal  extremity  of  the  bone,  and  thin, 
as  in  Casea.  The  hemispherical  capitellum  is  extended  into  a 
rounded  protuberance  on  the  outer  distal  side  of  the  convexity. 
The  right  ulna  was  found  attached  to  the  humerus  rectangularly; 
a  small  part  of  the  middle  of  its  shaft  is  missing.  It  is  a  stout  bone, 
with  a  well-developed  olecranon,  the  distal  extremity  expanded 
and  thickened,  and  nearly  semicircular  in  outline.  The  right 
radius,  found  connected  with  the  proximal  carpals,  is  nearly 
straight  on  its  outer  side,  deeply  concave  on  the  ulnar  border. 
The  proximal  end  is  transversely  truncated,  oval  in  outline  and 
gently  concave,  the  distal  border  rather  broad,  thinned  on  its 
ulnar  margin.  This  bone,  like  the  ulna,  is  concave  on  the  ventral 
side,  nearly  straight  on  the  dorsal.  The  carpals  of  both  sides  are 
preserved  in  part,  those  of  the  proximal  row  in  position,  as  also 
the  first  centrale  and  the  first  two  carpalia;  three  other  carpalia 
cannot  be  positively  located;  the  bones  of  the  fourth  finger  are 
articulated.  I  locate  the  bones  of  the  wrist  and  hand  in  the  figure 
as  it  seems  they  should  go,  those  unknown  or  doubtfully  known 
uniformly  shaded.  The  radiale  is  small  but  thick,  nearly  triangular 
in  shape  on  the  dorsal  side.  The  intermedium  is  unusually  large; 
its  position  as  regards  the  radius  is  shown  in  the  figure  as  it  is 
preserved  in  the  right  wrist.  The  ulnare  is  short.  I  am  not  sure 
but  a  little  of  the  lower  margin  is  gone,  as  it  is  figured.  The 
metacarpals  and  phalanges  are  very  stout,  as  are  also  the  claws. 

Of  the  right  innominate,  the  ilium,  the  whole  of  the  acetabulum, 
the  larger  part  of  the  pubis,  and  a  part  of  the  ischium  are  preserved 
attached  to  the  sacral  ribs.  The  pubis  and  ischium  appear  to  be 
very  much  like  those  of  Casea;  the  pubis  is  surely  not  of  the 
clepsydropid  type.  The  ilium,  however,  is  quite  unlike  that  of 
Casea,  in  that  it  is  prolonged  backward  and  not  at  all  forward, 


134  AMERICAN  PERMIAN  VERTEBRATES 

reaching  a  little  beyond  the  hind  end  of  the  ilio-ischiadic  suture. 
The  posterior  iliac  notch  is  deep  and  narrow,  its  upper  border, 
that  is,  the  lower  border  of  the  posterior  prolongation  of  the  ilium, 
is  quite  horizontal.  As  in  Casea,  the  internal  side  of  the  upper 
part  of  the  ilium  shows  no  indications  whatever  of  sutural  union 
with  the  sacral  ribs;  it  is  evident  that  their  attachment  was  liga- 
mentous  only  and  not  very  extensive. 

The  right  femur  as  preserved  is  in  good  condition,  but  its  con- 
dyles  are  a  little  worn.  The  digital  fossa  is  elongated  and  rather 
deep,  the  trochanteris  ridge  extending  a  little  beyond  the  lower 
end  of  the  fossa.  The  summit  of  the  trochanter  is  at  the  junction 
of  the  upper  and  middle  thirds  of  the  bone;  other  characters  will 
be  seen  in  the  figures. 

MEASUREMENTS 

Length  of  cervical  vertebra 12  mm. 

Transverse  diameter  of  centrum  of  same 12 

Length  of  centrum  opposite  the  hind  end  of  interclavicle  13 

Transverse  diameter  of  same 12 

Length  of  fifth  presacral  vertebra 16 

Length  of  fourth  presacral  vertebra 17 

Length  of  third  presacral  vertebra 17 

Length  of  second  presacral  vertebra 18 

Length  of  first  presacral  vertebra 19 

Transverse  diameter  of  centrum  of  same 20 

Length  of  sacral  vertebrae 60 

Expanse  of  first  sacral  ribs 80 

Extent  of  sacral  ribs  attachment 53 

Length  of  first  and  second  caudal  vertebrae 40 

It  is  evident  that  the  relationships  of  this  genus,  so  far  as  the 
parts  preserved  indicate,  are  with  Casea.  Indeed,  the  characters 
are  so  much  alike  that  until  the  ilium  was  secured  I  was  disposed 
to  place  them  both  in  the  same  genus.  The  backward  prolonga- 
tion of  the  ilium  is,  however,  more  than  a  specific  character.  The 
species  is  considerably  larger  than  Casea,  but  was  in  life  probably 
of  similar  proportions,  attaining  a  length  of  perhaps  four  and  a  half 
feet.  Unfortunately  nothing  whatever  is  known  of  the  skull. 


REPTILIA:  PLATYHYSTRIX  135 

GENUS  INCERTAE  SEDIS 
PLATYHYSTRIX 

Williston,  Science,  XXXIII,  631,  1911. 

Platyhystrix  rugosus.     Plates  XXXVI,  XXXVII. 

Ctenosaurus  rugosus  Case,  Bull.  Amer.  Mus.  Nat.  Hist.,  XXVIII,  1910. 
?  Zatrachys  apicalis  Cope,  Amer.  Nat.,  XV,  1020,  December,  1881. 

This  species  was  based  by  Case  on  a  few  neural  spines  of  remark- 
able character,  some  of  which  had  been  associated  by  Cope  with 
his  type  specimen  of  Zatrachys  apicalis,  evidently  the  ones  which 
he  describes  as  "  narrow  flat  bones,  which  I  suppose  to  be  neural 
spines,  which  are  ornamented  with  inosculating  ridges."  The 
species  was  referred  provisionally  by  Case  to  the  genus  Ctenosaurus 
Huene,  from  the  European  Trias.  The  essential  part  of  Case's 
description  is  as  follows: 

"The  spines  here  described  are  not  very  long,  the  base  is  nar- 
rowed with  almost  equal  antero-posterior  and  transverse  diameters. 
The  upper  portion  becomes  thinner,  and  is  elongated  in  the  antero- 
posterior  diameter.  The  sides  of  the  spines,  from  the  base  to  the 
top,  are  covered  with  small  irregular  bosses  similar  to  those  on  the 
skull  of  many  amphibians.  Some  of  the  spines  are  more  slender 
and  less  expanded  antero-posteriorly  at  the  top  than  others,  but 
all  have  the  characteristic  sculpture.  Fragments  of  scapulae  and 
limb  bones  associated  with  the  spines  are  typically  pelycosaurian 
in  form." 

In  the  Yale  collections  of  the  Arroya  bone-bed  of  New  Mexico 
are  several  spines  which  I  must  identify  specifically  with  those 
described  by  Case,  though  none  agrees  precisely  with  his  descrip- 
tion. One  of  these  is  shown  in  Plate  XXVI,  Fig.  i,  two-thirds 
natural  size.  It  is  nearly  complete;  some  of  the  fragments  from 
near  the  lower  end  had  crumbled  so  that  actual  contact  could  not 
be  made,  and  it  is  possible  that  the  interval  I  have  left  may  be 
slightly  too  great  or  too  small.  The  centrum  immediately  asso- 
ciated with  the  spine  in  all  probability  belongs  with  it,  though 


136  AMERICAN  PERMIAN  VERTEBRATES 

contact  could  not  be  secured.  In  its  porous  texture  and  peculiar 
black,  glossy  exterior  it  agrees  perfectly  with  the  lower  extremity 
of  the  spine,  and  is  unlike  other  bones  in  the  same  lot.  The  height 
of  the  spine  as  drawn  is  two  hundred  and  eighty  millimeters, 
considerably  more  than  twice  that  of  the  specimens  described  by 
Case  (one  hundred  and  thirteen  millimeters).  The  antero-pos- 
terior  expansion  of  the  upper  extremity  is  nearly  fifty-five  mil- 
limeters, while  the  length  of  the  centrum  is  but  twenty-three 
millimeters. 

This  spine  is  most  extraordinary.  It  is  very  thin  and  flat 
throughout,  save  at  the  lower  portion,  where  it  changes  into  the 
oval  stem.  The  upper  border,  also,  is  a  trifle  thicker  and  it  has 
a  gentle  sigmoid  curvature,  which,  however,  I  attribute  to  post- 
mortem causes.  On  the  lower  part,  especially,  there  are  longi- 
tudinal, somewhat  inosculating  ridges,  and,  scattered  irregularly 
over  the  bone,  are  a  considerable  number  of  small,  irregular  bosses, 
or  excrescences.  Throughout  this  portion  of  the  spine — that  is, 
above  the  oval  pedicel — the  anterior  and  posterior  borders  show 
narrow  groovings  for  ligamentous  attachments.  Associated  with 
these  spines  are  a  few  fragments  of  another,  apparently  from  the 
same  animal,  and  so  far  as  they  go,  quite  identical  with  the  one 
figured. 

The  spine  figured  in  Plate  XXXVII,  Fig.  6,  natural  size,  I  at 
first  ascribed  to  an  amphibian,  and  possibly  correctly,  but,  because 
of  the  almost  identical  appearance  of  the  bosses,  it  would  seem 
almost  certain  that  it  belongs  in  the  same  creature  as  do  the  longer 
spines.  It  resembles  very  much  a  lumbar  spine  of  Naosaurus  in 
its  peculiar  curvature.  Above  the  zygapophyses,  as  in  the  long 
spine,  the  bone  is  nearly  cylindrical  or  slightly  oval  in  cross-section. 
But  this  thickness  is  retained  throughout  or  is  even  greater  at  the 
beginning  and  the  end  of  the  rugosities;  and  the  upper  extremity 
is  expanded  somewhat,  club-shaped.  The  nodular  excrescences 
are  strongly  protuberant,  very  irregular  in  position  and  scarcely 
symmetrical  on  the  two  sides.  No  reptilian  centra  are  preserved, 
or  at  least  have  been  so  far  discovered  in  the  collection,  to  which 
this  spine  could  be  attached;  indeed,  the  arch  is  quite  similar  in 
form  to  those  of  Eryops,  found  associated  with  the  specimen.  There 


REPTILIA  :  SPECIES  INCERTAE  SEDIS  137 

are  two  or  three  small  intercentra  in  the  collection  of  suitable 
size  for  this  arch.  Notwithstanding  these  facts,  such  an  elongate 
curved  spine  for  an  amphibian  would  be  most  extraordinary  and 
unheard  of  and  the  absolute  identity  of  the  lateral  markings  in 
this  and  the  flat  spines  renders  it  almost  certain  that  they  all  pertain 
to  one  species  of  reptile. 

Associated  with  these  spines  are  a  lot  of  surface  fragments  of 
similar  spines.  They  all  agree  in  having  inosculating  ridges  and 
irregular  bosses.  Some  are  thicker  and  stouter,  like  those  described 
by  Case  for  the  base  of  his  spine,  having  their  diameters  nearly 
equal;  others  are  quite  thin,  but  they  all  agree  in  their  characters. 
Among  them  are  two  fragments  having  the  lower  end  of  the  lateral 
excavated  surface  with  a  short  interval  of  rounded  smooth  spine, 
and  then  on  each  side  a  very  irregular  large  nodosity,  the  spine 
again  contracting  below  them. 

If  there  are  two  different  forms  of  animals  represented  by  these 
various  specimens,  then  evidently  one  is  the  Ctenosaurus  rugosus 
of  Case;  the  ether,  Zatrachys  apicalis  of  Cope.  But  I  believe  that 
they  all  pertain  to  one  form,  which  may  be  Cope's  Z.  apicalis. 

Certain  it  is  that  the  creature  or  creatures  possessing  these  most 
peculiar  spine  structures  will  be  found  to  be  among  the  most  remark- 
able of  vertebrates. 

SPECIES  INCERTAE  SEDIS 

Numerous  limb  bones,  as  well  as  vertebrae,  from  the  Craddock 
bone-bed  are  indeterminable.  Not  only  because  of  their  intimate 
faunistic  association,  but  because  of  their  perfect  preservation 
and  unique  types  I  give  figures  and  brief  descriptions  of  some  of 
the  more  important  ones.  Some  are  undoubtedly  new  to  science, 
but  nothing  will  be  gained  by  giving  them  names.  To  facilitate 
reference  to  them,  however,  I  have  designated  them  by  arbitrary 
signs,  consecutive  letters  with  the  number  104,  the  lot  number 
under  which  they  are  registered  in  the  University  catalogue.  I  have 
figured  some  of  the  smaller  forms  only;  later  studies  of  the  ver- 
tebrae and  girdles  may  indicate  by  elimination  the  relationships  of 
some  of  the  forms.  It  is  very  probable  that  most  of  the  specimens 
here  described  belong  among  the  zygocrotaphic  reptiles. 


138  AMERICAN  PERMIAN  VERTEBRATES 

Femur  104  A  (Plate  XXX,  Fig.  4). — There  are  more  than 
twenty  femora  of  this  type,  all  of  the  same  or  nearly  equal  size, 
conclusively  indicating  their  adult  character.  The  articular  ends 
are  rather  sharply  edged,  indicating  more  or  less  cartilaginous 
surfaces,  but  not  nearly  to  the  extent  characteristic  of  Clepsydrops. 
The  digital  fossa  is  rather  large ;  there  is  no  distinctive  trochanter  or 
adductor  ridge.  The  shaft  in  the  middle  is  nearly  circular  in  cross- 
section.  The  popliteal  fossa  is  rather  shallowly  concave  and  broad. 

Tibia  104  B  (Plate  XXXIII,  Fig.  8).— There  are  two  complete 
tibiae  of  this  type,  and  parts  of  several  others.  They  are,  like  the 
larger  tibia,  shown  in  Plate  XXX,  Fig.  10,  deeply  concave  on  the 
ventral  side.  The  lower  end  is  sharply  truncate  and  transversely 
oval.  It  is  possible  that  this  tibia  belongs  with  femur  104  A,  but  it 
seems  to  be  too  long. 

Tibia  104  C  (Plate  XXXIII,  Fig.  7).— This  type,  of  which  I  have 
found  but  a  single  specimen,  agrees  so  well  with  the  larger  form 
provisionally  referred  to  Clepsydrops  that  it  may  be  merely  a 
juvenile  specimen.  Its  proportions,  however,  are  somewhat 
different,  but  perhaps  no  greater  than  those  observed  between  the 
juvenile  and  adult  femora  referred  to  Clepsydrops. 

Fibula  104  D  (Plate  XXXII,  Fig.  3).— A  very  slender  right 
fibula  of  peculiar  form.  The  surface  shown  is  nearly  in  one  plane. 
The  upper  articular  surface  is  very  oblique,  as  is  seen  in  the  photo- 
graph, and  is  of  an  elongate  crescentic  shape.  The  external  lower 
surface  turns  backward  and  is  gently  concave,  separated  from  the 
convex  dorsal  surface  by  a  rounded  ridge. 

Fibula  104  E  (Plate  XXXIII,  Fig.  9).— A  second  fibula  of 
precisely  the  same  length  as  the  preceding  and  of  like  slenderness 
is  quite  surely  of  a  different  genus.  The  upper  articular  surface 
is  not  oblique  and  the  tibiale  side  is  more  concave  in  outline,  nor 
is  the  lower  extremity  at  all  like  that  of  the  preceding  fibula,  but 
agrees  better  with  that  of  the  fibula  of  Varanosaurus. 

Fibula  104  F  (Plate  XXX,  Fig.  9). — This  fibula  may  possibly 
be  a  juvenile  form  of  that  shown  in  Plate  XXX,  Fig.  IT,  and 
referred  provisionally  to  Clepsydrops,  but  the  upper  extremity  is 
twisted  more  obliquely  to  the  shaft,  the  shaft  on  the  concave  side  is 
thinner,  the  lower  border  is  more  oblique  to  the  axis  of  the  bone,  etc. 


KEPT  I  LI  A  :  SPECIES  INCERTAE  SEDIS  139 

Radius  104  G  (Plate  XXXIII,  Fig.  6).— This,  the  largest  of  the 
radii  preserved,  indicates  an  animal  of  considerable  size  and 
slenderness.  The  upper  extremity  has  evidently  been  injured; 
its  expansion  is  nearly  as  great  as  that  of  the  lower  extremity,  but 
the  long  axis  of  its  articular  end  is  very  oblique  to  the  plane  of  the 
lower  end.  The  bone  is  very  concave  on  its  ventral  side,  the  dorsal 
border  nearly  in  one  plane  or  a  trifle  convex.  A  little  above  the 
distal  end  on  the  ulnar  side  there  is  a  sharp  ridge;  evidently  the 
small  radius  shown  in  fig.  5  belongs  to  the  same  species. 

Radius  104  H  (Plate  XXXIII,  Fig.  10).— This  small  radius, 
even  though  juvenile,  is  evidently  of  a  different  form  from  either  of 
those  previously  described.  The  two  ends  are  expanded  in  the 
same  plane,  the  bone  is  nearly  flat  on  the  ventral  side,  and  the  lower 
end  is  but  slightly  expanded.  There  are  in  addition  to  this,  other 
small  radii  of  less  slender  form. 

Radius  104  I  (Plate  XXXII,  Fig.  2).— It  is  not  improbable  that 
this  radius  may  belong  with  some  one  of  the  different  forms  of 
amphibians  represented  by  the  femora  and  humerus  described  on 
page  14,  which  I  refer  provisionally  to  Aspidosaurus  or  allied  new 
forms.  It  has,  however,  the  same  general  characters  of  the  more 
slender  radii  described. 

Tibia  104  J  (Plate  XXXII,  Fig.  5).— This  tibia,  of  considerable 
size,  is  very  peculiar  in  the  very  much  flattened  upper  end  (the 
lower  end  in  the  figure)  with  very  shallow  concavities  on  either  side 
of  the  cnemial  convexity.  It  is  not  curved  as  much  as  the  tibia 
referred  to  Clepsydrops,  and  is  very  unlike  that  form.  Its  unlike 
form  also  precludes  the  possibility  of  its  being  a  juvenile  specimen 
of  a  Dimetrodon. 

Ilium  104  K  (Plate  XXXI,  Fig.  i). — In  much  probability  this 
ilium  belongs  with  femur  104  A.  It  is  very  unlike  any  ilium 
hitherto  figured  or  described  from  the  Permian  of  Texas.  The 
upper  helmet-shaped  expansion  is  high  and  thin,  the  front  border 
is  thicker  and  curved  gently  forward,  the  upper  thin  border  convex 
throughout.  The  posterior  iliac  notch  is  very  small;  the  antero- 
posterior  diameter  of  the  bone  in  its  narrowest  place  much  less  than 
that  of  the  ilium  referred  to  Clepsydrops  (Fig.  2).  The  inner  side 
shows  rugosities  apparently  for  three  sacral  ribs,  but  this  is  not 
certain. 


EXPLANATION  OF  PLATES 

[  All  the  figures  are  by  the  author,  and  are  of  natural  size,  except  where  other- 
wise stated.] 

FRONTISPIECE. — Mounted  skeletons  of  Varanosaurus  brevirostris  Williston, 
and  Casea  broilii  Williston,  a  little  less  than  one-sixth  natural  size.  Walker 
Museum,  University  of  Chicago.  Skeletons  collected,  prepared,  and  mounted 
by  Paul  C.  Miller. 

PLATE  I. — Varanosaurus  brevirostris  Williston.  Fig.  i,  dorsal  ribs,  a,  &,  d, 
left,  from  behind,  c,  right,  dd,  same  as  d,  from  in  front;  Fig.  2,  odontoid  of 
atlas,  axis,  and  third  to  fifteenth  vertebrae,  from  the  side. 

PLATE  II. — Varanosaurus  brevirostris  Williston.  Fig.  2,  fourth  to  fif- 
teenth (thirteenth  to  twenty-fourth  presacral)  vertebrae  from  below;  Fig.  2, 
sixteenth  to  twenty-seventh  (first  to  twelfth  presacral)  vertebrae,  from  the  side; 
Fig.  3,  the  same,  from  below. 

PLATE  III. — Varanosaurus  brevirostris  Williston.  Sacral  and  caudal 
vertebrae  in  continuous  series  to  the  forty-seventh,  as  found  in  articulation; 
with  anterior  and  distal  chevrons. 

PLATE  IV. — Varanosaurus  brevirostris  Williston.  Fig.  i,  interclavicle 
and  clavicles  in  articulation;  Fig.  2,  interclavicle  from  left  side;  Fig.  3,  left 
clavicle,  from  below;  Fig.  4,  right  clavicle,  from  in  front;  Fig.  5,  right  scapula- 
coracoid,  from  behind;  Fig.  6,  right  proximal  tarsals,  a,  tibiale;  b,  fibulare; 
Fig.  7,  the  same,  ventral  side;  Fig.  8,  sacrum,  from  below. 

PLATE  V. — Varanosaurus  brevirostris  Williston.  Right  scapula.  Fig.  i, 
from  outer  side;  Fig.  2,  from  inner  side;  Fig.  3,  from  above;  Fig.  4,  from  below. 

PLATE  VI. — Varanosaurus  brevirostris  Williston.  Fig.  i,  right  humerus, 
ventral  side;  Fig.  2,  the  same,  ulnar  side;  Fig.  3,  the  same,  dorsal  side;  Fig.  4, 
the  same,  radial  side;  Fig.  5.  the  same,  distal  end;  Fig.  6,  the  same,  proximal 
end;  Fig.  7,  sacrum,  from  in  front;  Fig.  8,  first  presacral  vertebra,  from  in 
front;  Fig.  9,  twelfth  presacral  (fifteenth  postcranial)  vertebra,  from  behind. 

PLATE  VII. — Varanosaurus  brevirostris  Williston.  Fig.  i,  left  radius 
and  ulna,  dorsal  side;  Fig.  2,  the  same,  ventral  side;  Fig.  3,  left  ulna,  radial 
side;  Fig.  4,  left  radius,  ulnar  side;  Fig.  5,  ulnare,  ventral  side;  Fig.  6,  left 
ulna  of  another  individual,  dorsal  side;  Fig.  7,  a,  odontoid  of  undetermined 
pelycosaurian,  from  in  front,  b,  from  the  side,  c,  from  behind;  Fig.  8,  carpus  of 
Dimetrodon  incisivus  Cope,  ventral  side,  two-thirds  natural  size  (R,  radiale; 
U,  ulnare;  C  i,  2,  centralia;  1-5,  carpalia). 

PLATE  VIII. — Varanosaurus  brevirostris  Williston.  Left  forearm  and 
hand,  dorsal  side. 

140 


EXPLANATION  OF  PLATES  141 

PLATE  IX. — Varanosaurus  brevirostris  Williston.  Right  innominate.  Fig. 
i,  from  without;  Fig.  2,  from  within.  IL,  ilium;  76",  ischium;  PB,  pubis. 

PLATE  X. — Varanosaurus  brevirostris  Williston.  Pelvis,  from  below,  the 
lower  figure,  a  photograph,  two-thirds  natural  size. 

PLATE  XI. — Varanosaurus  brevirostris  Williston.  Pelvis  and  first  five 
caudal  vertebrae,  from  above. 

PLATE  XII. — Varanosaurus  brevirostris  Williston.  Fig.  i,  left  femur, 
ventral  side;  Fig.  2,  the  same,  fibular  side;  Fig.  3,  the  same,  tibial  side;  Fig.  4, 
the  same,  dorsal  side;  Fig.  5,  the  same,  distal  end;  Fig.  6,  left  tibia,  ventral 
side;  Fig.  7,  the  same,  dorsal  side;  Fig.  8,  the  same,  fibular  side;  Fig.  9,  the 
same,  inner  side;  Fig.  10,  the  same,  proximal  end;  Fig.  n,  the  same,  distal 
end. 

PLATE  XIII. — Varanosaurus  brevirostris  Williston.  Seymouria  baylorensis 
Broili.  Fig.  i,  Varanosaurus,  right  foot,  dorsal  side;  Fig.  2,  Varanosaurus, 
right  fibula,  ventral  side;  Fig.  3,  Varanosaurus,  right  fibula  of  another  indi- 
vidual, dorsal  side;  Fig.  4,  Seymouria,  anterior  vertebra,  from  the  side;  Fig.  5, 
the  same,  from  in  front;  Fig.  6,  Seymouria,  posterior  vertebrae,  from  below; 
Fig.  7,  the  same,  from  above;  Fig.  8,  the  same,  from  the  side. 

PLATE  XIV. — Casea  broilii  Williston.  No.  656.  Fig.  i,  first  seven  post- 
cranial  vertebrae,  a,  the  odontoid  from  side  and  behind,  b,  the  axis  from  behind; 
Fig.  2,  second  presacral  (twenty- third  postcranial)  vertebra  from  in  front, 
with  co-osified  ribs,  the  right  also  from  below;  Fig.  3,  right  mandible,  from 
outer  side;  Fig.  4,  the  same  from  inner  side,  without  articular;  Fig.  5,  man- 
dibles, from  above.  Fig.  6,  interclavicle. 

PLATE  XV. — Casea  broilii  Williston.  Third  postcranial  vertebra  from  side 
and  below;  eighth  to  twenty-fourth  (first  presacral)  vertebrae  from  the  side, 
the  fourteenth  also  from  below  and  the  seventeenth  from  above. 

PLATE  XVI. — Casea  broilii  Williston.  Fig.  i,  sacrum  and  first  seven 
caudal  vertebrae,  from  the  side,  the  sixth  also  from  below,  specimen  No.  655; 
Fig.  2,  first  ten  caudal  vertebrae,  from  the  side,  the  third,  fourth,  and  fifth 
also  from  below,  No.  656;  Fig.  3,  first  chevron,  from  behind,  No.  656. 

PLATE  XVII. — Casea  broilii  Williston.  No.  655.  Fig.  i,  fourteenth 
postcranial  vertebra,  with  ribs,  from  behind;  Fig.  2,  twenty-first  postcranial 
vertebra,  with  ribs,  from  behind;  Fig.  3,  twenty-second  vertebra,  with  ribs, 
from  in  front. 

PLATE  XVIII. — Casea  broilii  Williston.  Fig.  i,  10,  rib  of  tenth  postcranial 
vertebra;  12,  rib  of  twelfth  vertebra;  15,  rib  of  fifteenth  vertebra;  18,  rib  of 
eighteenth  vertebra;  Fig.  2,  second  caudal  vertebra,  from  below;  Fig.  3,  third 
sacral  vertebra,  from  behind;  Fig.  4,  first  sacral  vertebra,  from  in  front;  Fig.  2, 
specimen  No.  656;  all  others,  No.  657. 

PLATE  XIX. — Casea  broilii  Williston.  Fig.  i,  right  scapula  from  outer 
side;  Fig.  2,  left  scapula,  from  below;  Fig.  3,  right  scapula,  from  behind; 
Fig.  4,  two  distal  phalanges  of  thumb,  as  articulated;  Fig.  6,  fifth  metacarpal; 


142  AMERICAN  PERMIAN  VERTEBRATES 

Fig.  7,  fourth  metacarpal;  Fig.  8,  distal  caudal  vertebrae.  Figs.  1-7,  No.  655; 
Fig.  8,  No.  658. 

PLATE  XX. — Cased  broilii  Williston.  Specimen  655.  Fig.  i,  right 
humerus,  ventral  side,  with  a,  distal  end;  Fig.  2,  the  same,  dorsal  side;  Fig. 
3,  the  same,  ulnar  side;  Fig.  4,  right  ulna;  Fig.  5,  right  radius;  Fig.  6,  sacrum 
and  first  caudal  vertebra,  ventral  side. 

PLATE  XXI. — Casea  broilii  Williston.  Specimen  655.  Fig.  i,  left  innomi- 
nate, outer  side;  Fig.  2,  the  same,  inner  side,  il,  ilium,  is,  ischium,  pb,  pubis. 

PLATE  XXII. — Casea  broilii  Williston.  Specimen  655.  Fig.  i,  right 
femur,  dorsal  side  and  distal  end;  Fig.  2,  the  same,  ventral  side;  Fig.  3,  the 
same,  outer  side;  Fig.  4,  the  same,  tibial  side  and  proximal  end;  Fig.  5, 
right  tibia,  ventral  side  and  distal  end;  Fig,  6,  the  same,  outer  side  and  proximal 
end;  Fig.  7,  right  fibula,  dorsal  side  and  distal  end;  Fig.  8,  the  same,  tibial 
side  and  proximal  end. 

PLATE  XXIII. — Casea  broilii  Williston.  Specimen  655.  Fig.  i,  right 
hind  foot,  dorsal  side;  Fig.  2,  right  tibiale  and  fibulare,  proximal  ends;  Fig.  3, 
right  tibiale,  inner  side;  Fig.  4,  ungual  phalange;  Fig.  5,  outline  of  tarsal 
bones,  from  plantar  side;  Fig-.  6,  sacrum,  from  above. 

PLATE  XXIV. — Fig.  i,  Trispondylus  texensis  Williston,  right  femur,  ventral 
side,  with  attached  proximal  end  of  tibia,  two-thirds  natural  size;  Fig.  2,  the 
same,  inner  side;  Fig.  3,  Trematops  milleri  Williston,  left  femur,  ventral  side; 
Fig.  4,  the  same,  inner  side;  Fig.  5,  Captorhinus  illinoiensis  Williston,  left 
femur,  ventral  side;  Fig.  6,  proximal  end  of  same;  Fig.  7,  distal  end  of  same; 
Fig.  8,  Labidosaurus,  species,  right  femur,  ventral  side;  Fig.  9,  distal  end  of 
same;  Fig.  10,  proximal  end  of  same. 

PLATE  XXV. — Trispondylus  texensis  Williston.  Fig.  i,  right  humerus, 
ventral  side;  Fig.  2,  the  same,  outer  side;  Fig.  3,  proximal  end  of  radius;  Fig.  4, 
proximal  end  of  ulna;  Fig.  5,  distal  end  of  radius;  Fig.  6,  distal  end  of  ulna; 
Fig.  7,  metacarpal  and  phalanges,  as  articulated;  Fig.  8,  metacarpal;  Fig.  9, 
ulnare. 

PLATE  XXVI. — Seymour ia  bzylorensis  Broili.  Skull  and  anterior  verte- 
brae, from  above. 

PLATE  XXVII. — Seymouria  baylorensis  Broili.  Skull  and  pectoral  girdle, 
from  below. 

PLATE  XXVIII. — Seymouria  baylorensis  Broili.  Upper  figure,  skull  and 
pectoral  girdle,  from  the  side;  lower  figure,  the  skeleton  as  exposed  in  the 
nodule,  much  reduced. 

PLATE  XXIX. — Seymouria  baylorensis  Broili  (type  of  D.  anomalus  Willis- 
ton).  Fig.  i,  right  humerus,  a,  from  side,  b,  from  in  front;  Fig.  2,  left  tibia, 
ventral  side;  Fig.  3,  radius;  Fig.  4,  right  femur,  from  behind;  Fig.  5,  left 
femur,  from  Cacops  bone-bed,  natural  size;  Fig.  6,  undet.;  Fig.  7,  left  ilium, 
from  without;  Fig.  8,  posterior  dorsal  vertebra,  from  in  front;  Fig.  9,  dorsal 
centrum,  from  behind;  Fig.  10,  dorsal  centrum,  from  in  front;  Fig.  n,  the 


EXPLANATION  OF  PLATES  143 

same  from  above;  Fig.  12,  the  same,  from  the  side.  All  figures,  save  5,  twice 
natural  size  of  the  embryonic  specimen,  and  about  equal  to  adult  size. 

PLATE  XXX. — Craddock  bone-bed.  Fig.  i,  Clepsydrops,  left  femur, 
ventral  side  and  proximal  end;  Fig.  2,  Clepsydrops,  left  femur,  dorsal  side; 
Fig.  3,  Clepsydrops,  juvenile  left  femur,  dorsal  side;  Fig.  4,  gen.  nov.  left 
femur,  dorsal  side,  with  proximal  and  distal  ends;  Fig.  5,  Clepsydrops,  juvenile 
left  humerus;  Fig.  6,  pariotichid  genus  indet.,  left  femur,  dorsal  side;  Fig.  7, 
the  same,  ventral  side;  Fig.  8,  gen.  indet.  radius;  Fig.  9,  gen.  indet.  fibula; 
Fig.  10,  Clepsydrops  (?),  left  tibia,  ventral  side;  Fig.  n,  Clepsydrops  (?), 
fibula. 

PLATE  XXXI. — Craddock  bone-bed.  Fig.  i,  gen.  nov.  left  ilium,  outer 
side;  Fig.  2,  Clepsydrops,  left  ilium,  outer  side;  Fig.  3,  Clepsydrops,  right 
humerus,  ventral  side;  Fig.  4,  Clepsydrops,  left  ischium;  Fig.  5,  Clepsydrops 
(?),  quadrate,  inner  side;  Fig.  6,  the  same,  distal  end;  Fig.  8,  Clepsydrops  (?) 
articular,  from  above;  Fig.  9,  the  same  from  below;  Fig.  10,  Clepsydrops, 
fibulare. 

PLATE  XXXII.— Craddock  bone-bed.  Fig.  i,  Clepsydrops,  femur,  dorsal 
side;  Fig.  2,  radius,  indet.;  Fig.  3,  fibula,  indet.;  Fig.  4,  Aspidosaurus,  femur, 
ventral  side;  Fig.  5,  tibia  (reversed),  indet.;  Fig.  6,  Aspidosaurus,  femur, 
ventral  side;  Fig.  7,  Aspidosaurus  peltatus  Williston,  dorsal  shield,  from 
above;  Fig.  8,  diadectid  tooth;  Fig.  9,  Clepsydrops  (?),  astragalus,  from  in 
front;  Fig.  10,  astragalus,  indet.,  dorsal  side;  Fig.  n,  fibulare,  indet. 

PLATE  XXXIII. — Craddock  bone-bed.  Figs,  i,  2,  3,  4,  Aspidosaurus, 
spp.  femora,  ventral  side;  Figs.  5,  6,  radii,  indet.;  Figs.  7,  8,  gen.  nov.  tibiae, 
dorsal  side;  Fig.  9,  fibula,  indet.;  Fig.  10,  radius,  indet.;  Fig.  n,  Aspidosaurus, 
ilium,  from  without. 

PLATE  XXXIV. — New  Mexico,  Yale  collections.  Fig.  i,  Sphenacodon 
ferox  Marsh,  type,  left  dentary,  from  without;  Fig.  2,  Sphenacodon  fer ox,  left 
premaxilla,  from  within;  Fig.  3,  Ophiacodon  mirus  Marsh,  type,  right  dentary, 
from  without;  Fig.  4,  Ophiacodon,  right  clavicle,  external  side;  Fig.  5,  Nothodon 
lentus  Marsh,  type,  left  dentary, from  the  side;  Fig.  6,  the  same,  from  above; 
Fig.  7,  Nothodon  lentus,  posterior  tooth,  from  behind;  Fig.  8,  Eryops,  ungual 
phalanx;  Fig.  9,  Eryops,  sacral  rib;  Fig.  10,  Ophiacodon  ( ?),  right  neural  arch  of 
atlas;  Fig.  n,  the  same,  from  without. 

PLATE  XXXV. — New  Mexico,  Yale  collections.  Fig.  i,  Nothodon  lentus 
Marsh  (probably,  with  the  three  following,  a  part  of  type  specimen),  left  radius, 
with  proximal  end;  Fig.  2,  N.  lentus,  left  ulna,  ventral  side;  Fig.  3,  N.  lentus, 
left  fibula,  ventral  side;  Fig.  4,  N.  lentus,  left  tibia,  dorsal  side,  with  a,  proximal 
end;  Fig.  5,  Sphenacodon  (?)  Ophiacodon  (?),  right  humerus,  ventral  side; 
Fig.  6,  Ophiacodon,  tibia;  Fig.  7,  Ophiacodon  (?),  fibula;  Fig.  8,  Ophiacodon, 
left  ulna,  ventral  side;  Fig.  9,  the  same,  dorsal  side;  Fig.  10,  Ophiacodon, 
radius;  Fig.  n,  the  same,  ulnar  side.  Figures  two-thirds  natural  size. 

PLATE  XXXVI.— New  Mexico,   Yale  collections.     Fig.    i,   Platyhystrix 


144  AMERICAN  PERMIAN  VERTEBRATES 

rugosus  Case,  dorsal  vertebra,  two-thirds  natural  size;  Fig.  2,  Nothodon  lentus 
Marsh,  dorsal  vertebra;  Fig.  3,  Ophiacodon,  posterior  dorsal  vertebra;  Fig. 
4,  Ophiacodon  (?),  Sphenacodon  (?),  last  lumbar  and  first  sacral  vertebra, 
from  in  front;  Fig.  5,  Ophiacodon  mirus,  part  of  left  maxilla,  type  specimen. 

PLATE  XXXVII.— New  Mexico,  Yale  collections.  Fig.  i,  Sphenacodon 
mirus,  Marsh,  left  maxilla,  from  within  (part  of  type  specimen);  Fig.  2, 
Sphenacodon  ferox,  left  premaxilla,  from  without;  Fig.  3,  Ophiacodon  (?), 
Sphenacodon  (?),  left  femur,  dorsal  side;  Fig.  4,  Ophiacodon,  left  ilium,  from 
without;  Fig.  5,  the  same,  from  within;  Fig.  6,  Platyhystrix  rugosus  Case, 
spine  of  posterior  vertebra. 

PLATE  XXXVIII. — New  Mexico,  Yale  collections.  Aspidosaurus  novamex- 
icanus  Williston,  type  specimen,  from  above,  about  one-half  natural  size; 
Fig.  2,  Limnoscelis  paludis  Williston,  a  little  reduced;  Fig.  3,  Nothodon  lentus 
Marsh,  top  of  skull,  reduced. 


INDEX 


Adlachrymal  bone,  19 

Amphibia,  9 

Araeoscelis,  6 

Aspidosaurus   novomexicanus,    12;    pel- 

tatus,  13 

Baker,  Lawrence,  5 
Brachycnemius  dolichomerus,  77 
Broili,  Ferdinand,  48,  53,  85 
Cacops  bone-bed,  4 
Captorhinus,  68;   illinoiensis,  69 
Case,  E.  C.,  i 
Casea  broilii,  112 
Caseidae,  characters  of,  in 
Clear  Fork  division,  3 
Clepsydrops,  72;  natalis,  73 
Clepysydropidae,  72 
Conodectes,  48 
Cope,  E.  C.,  8 

Coracoid,  structure  of,  58,  98 
Cotylosauria,  characters  of,  15 
Craddock  bone-bed,  5 
Ctenosaurus  rugosus,  135 
Cummins,  W.  F.,  3 
Desmospondylus  anomalus,  49 
Diadectes,  16;  species,  23 
Diadectidae,  characters  of,  16 
Diasparactus,  34 

Dimetrodon  incisivus,  76;  navajoicus,  84 
Diplodocus,  97 
Dissorophus,  13 
Double  Mountain  division,  3 
Dromopus  agilis,  40 
Elcabrosaurus,  80 
Eosauravus  copei,  44 
Erpetosuchus  kansensis,  32 
Eryopidae,  characters  of,  9 
Eryops,  13;  grandis,  10 
Euchirosaurus,  n 
Gibb,  Hugh,  25 
Huene,  F.  v.,  92 
Kadaliosaurus,  7 
Labidosaurus,  mandible  of,  31 
Limnoscelidae,  characters  of,  23 
Limnoscelis  paludis,  23;  relationships  of, 

47 


Marsh,  O.  C.,  7 

Mesosaurus,  in 

Miller,  Paul  C.,  i,  140 

Moodie,  R.  L.,  64 

Mosasauria,  evolution  of  paddles,  45 

New  Mexico,  Penman  of,  7 

Nothodon  lentus,  16 

Nothodontidae,  16 

Ophiacodon  minis,  81 

Otocoelus  mimeticus,  13 

Pareiasaurus,  47 

Pariotichidae,  characters  of,  68 

Paroccipital,  116 

Pelycosauria,  70 

Phalangeal  formula,  40 

Platyhystrix  rugosus,  135 

Poecilospondylus,  80 

Poliosauridae,  characters  of,  80 

Poliosaurus,  80 

Postnarial  bone,  19 

Prearticular  bone,  32 

Proganosauria,  relationships  of,  in 

Propappus,  47 

Reptilia,  15;  origin  of,  64;  tarsus  of, 
primitive,  44 

Schuchert,  Charles,  i 

Seymouria  baylorensis,  48;  relation- 
ships of,  63 

Seymouriidae,  characters  of,  48 

Species  incertae  sedis,  137 

Sphenacodon  ferox,  78 

Sphenacodontidae,  72 

Stegocephala,  9 

Stereosternum,  in 

Tapinocephalus,  92 

Temnospondyli,  characters  of,  9 

Temporal  arches  and  vacuities,  92 

Therapsida,  71 

Theromorpha,  characters  of,  70 

Theropleura  retroversa,  82 

Trispondylus  texensis,  131 

Varanosaurus  acutirostris,  85;  breviros- 
tris,  85;  relationships  of,  109 

Wichita  division,  3 

Zatrachys  apicalis,  135 


145 


\;s  -•;, :    r  .V<     : 

-  -  .  ^ ,.  t  w  >•  k  -  ... 


i 


• 


PLATE  IV 


WiUiston 


VARANOSAURUS 


PLATE  V 


VARAXOSAURUS 


PLATE  VI 


YARANOSAHRUS 


PLATE  VII 


r 


Wil  listen 


YARAXOSAURUS,  DIMETRODOX 


PLATE  VIII 


IV 


VARANOSAURUS 


PLATE  IX 


VARAXOSAURUS 


PLATE  X 


YARANOSAURUS 


PLATE  XI 


VAKANOSAURUS 


PLATE  XII 


S.W.W.del. 


YARANOSAURUS 


PLATE  XIII 


YARAXOSAURUS,  SEYMOURIA 


PLATE  XIV 


CASEA 


x 

:=: 


co 


PLATE  XVIII 


CASEA 


PLATE  XIX 


CASEA 


PLATE  XX 


SWW 


CASEA 


PLATE  XXI 


CASEA 


PLATE  XXII 


CASEA 


PLATE  XXIII 


CASEA 


PLATE  XXIV 


TRISPOXDYLUS,  CAPTORHINUS 


PLATE  XXV 


TRISPONDYLUS 


PLATE  XXVI 


SEVMOURIA 


PLATE  XXVII 


SEYMOURIA 


PLATE  XXIX 


SEYMOURIA 


PLATE  XXX 


CLEPSYDROPS 


PLATE  XXXI 


CLEPSYDROPS 


PLATE  XXXII 


CRADDOCK  BONE-BED 


PLATE  XXXIII 


CRADDOCK  BONE-BED 


PLATE  XXXV 


SPHEXACODOX,  OPHIACODOX,  XOTHODOX 


PLATE  XXXVI 


sww 


NOTHODOX,  OPHIACODOX,  PLATYHYSTRIX 


14  DAY  USE 

FROM  WHICH 

SCIENCES  LIDRARY 


RETURKL  TO  DESK  FROM  WHICH  BORROWED 


This  book  is  due  on  the  last  date  stamped  below,  or 

on  the  date  to  which  renewed. 
Renewed  books  are  subject  to  immediate  recall. 


LD  21-50m-4,'63 
(D6471slO)476 


General  Library 

University  of  California 

Berkeley 


